Swiftgram/Source/ASCollectionView.mm
Adlai Holler f2c85fdc32 Fix Collection Item Index Path Conversion (#262)
* Fix the conversion order for collection index paths

* Update the changelog
2017-05-11 10:44:21 -07:00

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//
// ASCollectionView.mm
// Texture
//
// Copyright (c) 2014-present, Facebook, Inc. All rights reserved.
// This source code is licensed under the BSD-style license found in the
// LICENSE file in the /ASDK-Licenses directory of this source tree. An additional
// grant of patent rights can be found in the PATENTS file in the same directory.
//
// Modifications to this file made after 4/13/2017 are: Copyright (c) 2017-present,
// Pinterest, Inc. Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
#import <AsyncDisplayKit/ASAssert.h>
#import <AsyncDisplayKit/ASBatchFetching.h>
#import <AsyncDisplayKit/ASDelegateProxy.h>
#import <AsyncDisplayKit/ASCellNode+Internal.h>
#import <AsyncDisplayKit/ASCollectionElement.h>
#import <AsyncDisplayKit/ASCollectionInternal.h>
#import <AsyncDisplayKit/ASCollectionLayout.h>
#import <AsyncDisplayKit/ASCollectionViewLayoutController.h>
#import <AsyncDisplayKit/ASCollectionViewLayoutFacilitatorProtocol.h>
#import <AsyncDisplayKit/ASCollectionViewFlowLayoutInspector.h>
#import <AsyncDisplayKit/ASDataController.h>
#import <AsyncDisplayKit/ASDisplayNodeExtras.h>
#import <AsyncDisplayKit/ASDisplayNode+FrameworkPrivate.h>
#import <AsyncDisplayKit/ASElementMap.h>
#import <AsyncDisplayKit/ASInternalHelpers.h>
#import <AsyncDisplayKit/UICollectionViewLayout+ASConvenience.h>
#import <AsyncDisplayKit/ASRangeController.h>
#import <AsyncDisplayKit/_ASCollectionViewCell.h>
#import <AsyncDisplayKit/_ASDisplayLayer.h>
#import <AsyncDisplayKit/_ASCollectionReusableView.h>
#import <AsyncDisplayKit/ASPagerNode.h>
#import <AsyncDisplayKit/ASSectionContext.h>
#import <AsyncDisplayKit/ASCollectionView+Undeprecated.h>
#import <AsyncDisplayKit/_ASHierarchyChangeSet.h>
#import <AsyncDisplayKit/CoreGraphics+ASConvenience.h>
#import <AsyncDisplayKit/ASLayout.h>
#import <AsyncDisplayKit/ASThread.h>
/**
* A macro to get self.collectionNode and assign it to a local variable, or return
* the given value if nil.
*
* Previously we would set ASCollectionNode's dataSource & delegate to nil
* during dealloc. However, our asyncDelegate & asyncDataSource must be set on the
* main thread, so if the node is deallocated off-main, we won't learn about the change
* until later on. Since our @c collectionNode parameter to delegate methods (e.g.
* collectionNode:didEndDisplayingItemWithNode:) is nonnull, it's important that we never
* unintentionally pass nil (this will crash in Swift, in production). So we can use
* this macro to ensure that our node is still alive before calling out to the user
* on its behalf.
*/
#define GET_COLLECTIONNODE_OR_RETURN(__var, __val) \
ASCollectionNode *__var = self.collectionNode; \
if (__var == nil) { \
return __val; \
}
/// What, if any, invalidation should we perform during the next -layoutSubviews.
typedef NS_ENUM(NSUInteger, ASCollectionViewInvalidationStyle) {
/// Perform no invalidation.
ASCollectionViewInvalidationStyleNone,
/// Perform invalidation with animation (use an empty batch update).
ASCollectionViewInvalidationStyleWithoutAnimation,
/// Perform invalidation without animation (use -invalidateLayout).
ASCollectionViewInvalidationStyleWithAnimation,
};
static const NSUInteger kASCollectionViewAnimationNone = UITableViewRowAnimationNone;
/// Used for all cells and supplementaries. UICV keys by supp-kind+reuseID so this is plenty.
static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
#pragma mark -
#pragma mark ASCollectionView.
@interface ASCollectionView () <ASRangeControllerDataSource, ASRangeControllerDelegate, ASDataControllerSource, ASCellNodeInteractionDelegate, ASDelegateProxyInterceptor, ASBatchFetchingScrollView, ASCALayerExtendedDelegate, UICollectionViewDelegateFlowLayout> {
ASCollectionViewProxy *_proxyDataSource;
ASCollectionViewProxy *_proxyDelegate;
ASDataController *_dataController;
ASRangeController *_rangeController;
ASCollectionViewLayoutController *_layoutController;
id<ASCollectionViewLayoutInspecting> _defaultLayoutInspector;
__weak id<ASCollectionViewLayoutInspecting> _layoutInspector;
NSMutableSet *_cellsForVisibilityUpdates;
NSMutableSet *_cellsForLayoutUpdates;
id<ASCollectionViewLayoutFacilitatorProtocol> _layoutFacilitator;
CGFloat _leadingScreensForBatching;
BOOL _inverted;
NSUInteger _superBatchUpdateCount;
BOOL _isDeallocating;
ASBatchContext *_batchContext;
CGSize _lastBoundsSizeUsedForMeasuringNodes;
NSMutableSet *_registeredSupplementaryKinds;
CGPoint _deceleratingVelocity;
BOOL _zeroContentInsets;
ASCollectionViewInvalidationStyle _nextLayoutInvalidationStyle;
/**
* Our layer, retained. Under iOS < 9, when collection views are removed from the hierarchy,
* their layers may be deallocated and become dangling pointers. This puts the collection view
* into a very dangerous state where pretty much any call will crash it. So we manually retain our layer.
*
* You should never access this, and it will be nil under iOS >= 9.
*/
CALayer *_retainedLayer;
/**
* If YES, the `UICollectionView` will reload its data on next layout pass so we should not forward any updates to it.
* Rationale:
* In `reloadData`, a collection view invalidates its data and marks itself as needing reload, and waits until `layoutSubviews` to requery its data source.
* This can lead to data inconsistency problems.
* Say you have an empty collection view. You call `reloadData`, then immediately insert an item into your data source and call `insertItemsAtIndexPaths:[0,0]`.
* You will get an assertion failure saying `Invalid number of items in section 0.
* The number of items after the update (1) must be equal to the number of items before the update (1) plus or minus the items added and removed (1 added, 0 removed).`
* The collection view never queried your data source before the update to see that it actually had 0 items.
*/
BOOL _superIsPendingDataLoad;
/**
* It's important that we always check for batch fetching at least once, but also
* that we do not check for batch fetching for empty updates (as that may cause an infinite
* loop of batch fetching, where the batch completes and performBatchUpdates: is called without
* actually making any changes.) So to handle the case where a collection is completely empty
* (0 sections) we always check at least once after each update (initial reload is the first update.)
*/
BOOL _hasEverCheckedForBatchFetchingDueToUpdate;
/**
* The change set that we're currently building, if any.
*/
_ASHierarchyChangeSet *_changeSet;
/**
* Counter used to keep track of nested batch updates.
*/
NSInteger _batchUpdateCount;
struct {
unsigned int scrollViewDidScroll:1;
unsigned int scrollViewWillBeginDragging:1;
unsigned int scrollViewDidEndDragging:1;
unsigned int scrollViewWillEndDragging:1;
unsigned int scrollViewDidEndDecelerating:1;
unsigned int collectionViewWillDisplayNodeForItem:1;
unsigned int collectionViewWillDisplayNodeForItemDeprecated:1;
unsigned int collectionViewDidEndDisplayingNodeForItem:1;
unsigned int collectionViewShouldSelectItem:1;
unsigned int collectionViewDidSelectItem:1;
unsigned int collectionViewShouldDeselectItem:1;
unsigned int collectionViewDidDeselectItem:1;
unsigned int collectionViewShouldHighlightItem:1;
unsigned int collectionViewDidHighlightItem:1;
unsigned int collectionViewDidUnhighlightItem:1;
unsigned int collectionViewShouldShowMenuForItem:1;
unsigned int collectionViewCanPerformActionForItem:1;
unsigned int collectionViewPerformActionForItem:1;
unsigned int collectionViewWillBeginBatchFetch:1;
unsigned int shouldBatchFetchForCollectionView:1;
unsigned int collectionNodeWillDisplayItem:1;
unsigned int collectionNodeDidEndDisplayingItem:1;
unsigned int collectionNodeShouldSelectItem:1;
unsigned int collectionNodeDidSelectItem:1;
unsigned int collectionNodeShouldDeselectItem:1;
unsigned int collectionNodeDidDeselectItem:1;
unsigned int collectionNodeShouldHighlightItem:1;
unsigned int collectionNodeDidHighlightItem:1;
unsigned int collectionNodeDidUnhighlightItem:1;
unsigned int collectionNodeShouldShowMenuForItem:1;
unsigned int collectionNodeCanPerformActionForItem:1;
unsigned int collectionNodePerformActionForItem:1;
unsigned int collectionNodeWillBeginBatchFetch:1;
unsigned int collectionNodeWillDisplaySupplementaryElement:1;
unsigned int collectionNodeDidEndDisplayingSupplementaryElement:1;
unsigned int shouldBatchFetchForCollectionNode:1;
// Interop flags
unsigned int interop:1;
unsigned int interopWillDisplayCell:1;
unsigned int interopDidEndDisplayingCell:1;
} _asyncDelegateFlags;
struct {
unsigned int collectionViewNodeForItem:1;
unsigned int collectionViewNodeBlockForItem:1;
unsigned int collectionViewNodeForSupplementaryElement:1;
unsigned int numberOfSectionsInCollectionView:1;
unsigned int collectionViewNumberOfItemsInSection:1;
unsigned int collectionNodeNodeForItem:1;
unsigned int collectionNodeNodeBlockForItem:1;
unsigned int collectionNodeNodeForSupplementaryElement:1;
unsigned int collectionNodeNodeBlockForSupplementaryElement:1;
unsigned int collectionNodeSupplementaryElementKindsInSection:1;
unsigned int numberOfSectionsInCollectionNode:1;
unsigned int collectionNodeNumberOfItemsInSection:1;
unsigned int collectionNodeContextForSection:1;
// Whether this data source conforms to ASCollectionDataSourceInterop
unsigned int interop:1;
// Whether this interop data source returns YES from +dequeuesCellsForNodeBackedItems
unsigned int interopAlwaysDequeue:1;
// Whether this interop data source implements viewForSupplementaryElementOfKind:
unsigned int interopViewForSupplementaryElement:1;
} _asyncDataSourceFlags;
struct {
unsigned int constrainedSizeForSupplementaryNodeOfKindAtIndexPath:1;
unsigned int supplementaryNodesOfKindInSection:1;
unsigned int didChangeCollectionViewDataSource:1;
unsigned int didChangeCollectionViewDelegate:1;
} _layoutInspectorFlags;
BOOL _hasDataControllerLayoutDelegate;
}
@end
@implementation ASCollectionView
{
__weak id<ASCollectionDelegate> _asyncDelegate;
__weak id<ASCollectionDataSource> _asyncDataSource;
}
// Using _ASDisplayLayer ensures things like -layout are properly forwarded to ASCollectionNode.
+ (Class)layerClass
{
return [_ASDisplayLayer class];
}
#pragma mark -
#pragma mark Lifecycle.
- (instancetype)initWithCollectionViewLayout:(UICollectionViewLayout *)layout
{
return [self initWithFrame:CGRectZero collectionViewLayout:layout];
}
- (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout
{
return [self _initWithFrame:frame collectionViewLayout:layout layoutFacilitator:nil owningNode:nil eventLog:nil];
}
- (instancetype)_initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout layoutFacilitator:(id<ASCollectionViewLayoutFacilitatorProtocol>)layoutFacilitator owningNode:(ASCollectionNode *)owningNode eventLog:(ASEventLog *)eventLog
{
if (!(self = [super initWithFrame:frame collectionViewLayout:layout]))
return nil;
// Disable UICollectionView prefetching. Use super, because self disables this method.
// Experiments done by Instagram show that this option being YES (default)
// when unused causes a significant hit to scroll performance.
// https://github.com/Instagram/IGListKit/issues/318
if (AS_AT_LEAST_IOS10) {
super.prefetchingEnabled = NO;
}
_layoutController = [[ASCollectionViewLayoutController alloc] initWithCollectionView:self];
_rangeController = [[ASRangeController alloc] init];
_rangeController.dataSource = self;
_rangeController.delegate = self;
_rangeController.layoutController = _layoutController;
_dataController = [[ASDataController alloc] initWithDataSource:self node:owningNode eventLog:eventLog];
_dataController.delegate = _rangeController;
_batchContext = [[ASBatchContext alloc] init];
_leadingScreensForBatching = 2.0;
_lastBoundsSizeUsedForMeasuringNodes = self.bounds.size;
_layoutFacilitator = layoutFacilitator;
_proxyDelegate = [[ASCollectionViewProxy alloc] initWithTarget:nil interceptor:self];
super.delegate = (id<UICollectionViewDelegate>)_proxyDelegate;
_proxyDataSource = [[ASCollectionViewProxy alloc] initWithTarget:nil interceptor:self];
super.dataSource = (id<UICollectionViewDataSource>)_proxyDataSource;
_registeredSupplementaryKinds = [NSMutableSet set];
_cellsForVisibilityUpdates = [NSMutableSet set];
_cellsForLayoutUpdates = [NSMutableSet set];
self.backgroundColor = [UIColor whiteColor];
[self registerClass:[_ASCollectionViewCell class] forCellWithReuseIdentifier:kReuseIdentifier];
if (!AS_AT_LEAST_IOS9) {
_retainedLayer = self.layer;
}
[self _configureCollectionViewLayout:layout];
return self;
}
- (void)dealloc
{
ASDisplayNodeAssertMainThread();
ASDisplayNodeCAssert(_batchUpdateCount == 0, @"ASCollectionView deallocated in the middle of a batch update.");
// Sometimes the UIKit classes can call back to their delegate even during deallocation, due to animation completion blocks etc.
_isDeallocating = YES;
[self setAsyncDelegate:nil];
[self setAsyncDataSource:nil];
// Data controller & range controller may own a ton of nodes, let's deallocate those off-main.
ASPerformBackgroundDeallocation(_dataController);
ASPerformBackgroundDeallocation(_rangeController);
}
#pragma mark -
#pragma mark Overrides.
- (void)reloadDataWithCompletion:(void (^)())completion
{
ASDisplayNodeAssertMainThread();
if (! _dataController.initialReloadDataHasBeenCalled) {
// If this is the first reload, forward to super immediately to prevent it from triggering more "initial" loads while our data controller is working.
_superIsPendingDataLoad = YES;
[super reloadData];
}
void (^batchUpdatesCompletion)(BOOL);
if (completion) {
batchUpdatesCompletion = ^(BOOL) {
completion();
};
}
[self performBatchUpdates:^{
[_changeSet reloadData];
} completion:batchUpdatesCompletion];
}
- (void)reloadData
{
[self reloadDataWithCompletion:nil];
}
- (void)scrollToItemAtIndexPath:(NSIndexPath *)indexPath atScrollPosition:(UICollectionViewScrollPosition)scrollPosition animated:(BOOL)animated
{
if ([self validateIndexPath:indexPath]) {
[super scrollToItemAtIndexPath:indexPath atScrollPosition:scrollPosition animated:animated];
}
}
- (void)reloadDataImmediately
{
ASDisplayNodeAssertMainThread();
[self reloadData];
[self waitUntilAllUpdatesAreCommitted];
}
- (void)relayoutItems
{
[_dataController relayoutAllNodes];
}
- (void)waitUntilAllUpdatesAreCommitted
{
ASDisplayNodeAssertMainThread();
if (_batchUpdateCount > 0) {
// This assertion will be enabled soon.
// ASDisplayNodeFailAssert(@"Should not call %@ during batch update", NSStringFromSelector(_cmd));
return;
}
[_dataController waitUntilAllUpdatesAreCommitted];
}
- (void)setDataSource:(id<UICollectionViewDataSource>)dataSource
{
// UIKit can internally generate a call to this method upon changing the asyncDataSource; only assert for non-nil. We also allow this when we're doing interop.
ASDisplayNodeAssert(_asyncDelegateFlags.interop || dataSource == nil, @"ASCollectionView uses asyncDataSource, not UICollectionView's dataSource property.");
}
- (void)setDelegate:(id<UICollectionViewDelegate>)delegate
{
// Our UIScrollView superclass sets its delegate to nil on dealloc. Only assert if we get a non-nil value here. We also allow this when we're doing interop.
ASDisplayNodeAssert(_asyncDelegateFlags.interop || delegate == nil, @"ASCollectionView uses asyncDelegate, not UICollectionView's delegate property.");
}
- (void)proxyTargetHasDeallocated:(ASDelegateProxy *)proxy
{
if (proxy == _proxyDelegate) {
[self setAsyncDelegate:nil];
} else if (proxy == _proxyDataSource) {
[self setAsyncDataSource:nil];
}
}
- (id<ASCollectionDataSource>)asyncDataSource
{
return _asyncDataSource;
}
- (void)setAsyncDataSource:(id<ASCollectionDataSource>)asyncDataSource
{
// Changing super.dataSource will trigger a setNeedsLayout, so this must happen on the main thread.
ASDisplayNodeAssertMainThread();
// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle
// the (common) case of nilling the asyncDataSource in the ViewController's dealloc. In this case our _asyncDataSource
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to hold a strong
// reference to the old dataSource in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
NS_VALID_UNTIL_END_OF_SCOPE id oldDataSource = super.dataSource;
if (asyncDataSource == nil) {
_asyncDataSource = nil;
_proxyDataSource = _isDeallocating ? nil : [[ASCollectionViewProxy alloc] initWithTarget:nil interceptor:self];
_asyncDataSourceFlags = {};
} else {
_asyncDataSource = asyncDataSource;
_proxyDataSource = [[ASCollectionViewProxy alloc] initWithTarget:_asyncDataSource interceptor:self];
_asyncDataSourceFlags.collectionViewNodeForItem = [_asyncDataSource respondsToSelector:@selector(collectionView:nodeForItemAtIndexPath:)];
_asyncDataSourceFlags.collectionViewNodeBlockForItem = [_asyncDataSource respondsToSelector:@selector(collectionView:nodeBlockForItemAtIndexPath:)];
_asyncDataSourceFlags.numberOfSectionsInCollectionView = [_asyncDataSource respondsToSelector:@selector(numberOfSectionsInCollectionView:)];
_asyncDataSourceFlags.collectionViewNumberOfItemsInSection = [_asyncDataSource respondsToSelector:@selector(collectionView:numberOfItemsInSection:)];
_asyncDataSourceFlags.collectionViewNodeForSupplementaryElement = [_asyncDataSource respondsToSelector:@selector(collectionView:nodeForSupplementaryElementOfKind:atIndexPath:)];
_asyncDataSourceFlags.collectionNodeNodeForItem = [_asyncDataSource respondsToSelector:@selector(collectionNode:nodeForItemAtIndexPath:)];
_asyncDataSourceFlags.collectionNodeNodeBlockForItem = [_asyncDataSource respondsToSelector:@selector(collectionNode:nodeBlockForItemAtIndexPath:)];
_asyncDataSourceFlags.numberOfSectionsInCollectionNode = [_asyncDataSource respondsToSelector:@selector(numberOfSectionsInCollectionNode:)];
_asyncDataSourceFlags.collectionNodeNumberOfItemsInSection = [_asyncDataSource respondsToSelector:@selector(collectionNode:numberOfItemsInSection:)];
_asyncDataSourceFlags.collectionNodeContextForSection = [_asyncDataSource respondsToSelector:@selector(collectionNode:contextForSection:)];
_asyncDataSourceFlags.collectionNodeNodeForSupplementaryElement = [_asyncDataSource respondsToSelector:@selector(collectionNode:nodeForSupplementaryElementOfKind:atIndexPath:)];
_asyncDataSourceFlags.collectionNodeNodeBlockForSupplementaryElement = [_asyncDataSource respondsToSelector:@selector(collectionNode:nodeBlockForSupplementaryElementOfKind:atIndexPath:)];
_asyncDataSourceFlags.collectionNodeSupplementaryElementKindsInSection = [_asyncDataSource respondsToSelector:@selector(collectionNode:supplementaryElementKindsInSection:)];
_asyncDataSourceFlags.interop = [_asyncDataSource conformsToProtocol:@protocol(ASCollectionDataSourceInterop)];
if (_asyncDataSourceFlags.interop) {
id<ASCollectionDataSourceInterop> interopDataSource = (id<ASCollectionDataSourceInterop>)_asyncDataSource;
_asyncDataSourceFlags.interopAlwaysDequeue = [[interopDataSource class] respondsToSelector:@selector(dequeuesCellsForNodeBackedItems)] && [[interopDataSource class] dequeuesCellsForNodeBackedItems];
_asyncDataSourceFlags.interopViewForSupplementaryElement = [interopDataSource respondsToSelector:@selector(collectionView:viewForSupplementaryElementOfKind:atIndexPath:)];
}
ASDisplayNodeAssert(_asyncDataSourceFlags.collectionNodeNumberOfItemsInSection || _asyncDataSourceFlags.collectionViewNumberOfItemsInSection, @"Data source must implement collectionNode:numberOfItemsInSection:");
ASDisplayNodeAssert(_asyncDataSourceFlags.collectionNodeNodeBlockForItem
|| _asyncDataSourceFlags.collectionNodeNodeForItem
|| _asyncDataSourceFlags.collectionViewNodeBlockForItem
|| _asyncDataSourceFlags.collectionViewNodeForItem, @"Data source must implement collectionNode:nodeBlockForItemAtIndexPath: or collectionNode:nodeForItemAtIndexPath:");
}
_dataController.validationErrorSource = asyncDataSource;
super.dataSource = (id<UICollectionViewDataSource>)_proxyDataSource;
//Cache results of layoutInspector to ensure flags are up to date if getter lazily loads a new one.
id<ASCollectionViewLayoutInspecting> layoutInspector = self.layoutInspector;
if (_layoutInspectorFlags.didChangeCollectionViewDataSource) {
[layoutInspector didChangeCollectionViewDataSource:asyncDataSource];
}
}
- (id<ASCollectionDelegate>)asyncDelegate
{
return _asyncDelegate;
}
- (void)setAsyncDelegate:(id<ASCollectionDelegate>)asyncDelegate
{
// Changing super.delegate will trigger a setNeedsLayout, so this must happen on the main thread.
ASDisplayNodeAssertMainThread();
// Note: It's common to check if the value hasn't changed and short-circuit but we aren't doing that here to handle
// the (common) case of nilling the asyncDelegate in the ViewController's dealloc. In this case our _asyncDelegate
// will return as nil (ARC magic) even though the _proxyDataSource still exists. It's really important to hold a strong
// reference to the old delegate in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
NS_VALID_UNTIL_END_OF_SCOPE id oldDelegate = super.delegate;
if (asyncDelegate == nil) {
_asyncDelegate = nil;
_proxyDelegate = _isDeallocating ? nil : [[ASCollectionViewProxy alloc] initWithTarget:nil interceptor:self];
_asyncDelegateFlags = {};
} else {
_asyncDelegate = asyncDelegate;
_proxyDelegate = [[ASCollectionViewProxy alloc] initWithTarget:_asyncDelegate interceptor:self];
_asyncDelegateFlags.scrollViewDidScroll = [_asyncDelegate respondsToSelector:@selector(scrollViewDidScroll:)];
_asyncDelegateFlags.scrollViewWillEndDragging = [_asyncDelegate respondsToSelector:@selector(scrollViewWillEndDragging:withVelocity:targetContentOffset:)];
_asyncDelegateFlags.scrollViewDidEndDecelerating = [_asyncDelegate respondsToSelector:@selector(scrollViewDidEndDecelerating:)];
_asyncDelegateFlags.scrollViewWillBeginDragging = [_asyncDelegate respondsToSelector:@selector(scrollViewWillBeginDragging:)];
_asyncDelegateFlags.scrollViewDidEndDragging = [_asyncDelegate respondsToSelector:@selector(scrollViewDidEndDragging:willDecelerate:)];
_asyncDelegateFlags.collectionViewWillDisplayNodeForItem = [_asyncDelegate respondsToSelector:@selector(collectionView:willDisplayNode:forItemAtIndexPath:)];
if (_asyncDelegateFlags.collectionViewWillDisplayNodeForItem == NO) {
_asyncDelegateFlags.collectionViewWillDisplayNodeForItemDeprecated = [_asyncDelegate respondsToSelector:@selector(collectionView:willDisplayNodeForItemAtIndexPath:)];
}
_asyncDelegateFlags.collectionViewDidEndDisplayingNodeForItem = [_asyncDelegate respondsToSelector:@selector(collectionView:didEndDisplayingNode:forItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewWillBeginBatchFetch = [_asyncDelegate respondsToSelector:@selector(collectionView:willBeginBatchFetchWithContext:)];
_asyncDelegateFlags.shouldBatchFetchForCollectionView = [_asyncDelegate respondsToSelector:@selector(shouldBatchFetchForCollectionView:)];
_asyncDelegateFlags.collectionViewShouldSelectItem = [_asyncDelegate respondsToSelector:@selector(collectionView:shouldSelectItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewDidSelectItem = [_asyncDelegate respondsToSelector:@selector(collectionView:didSelectItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewShouldDeselectItem = [_asyncDelegate respondsToSelector:@selector(collectionView:shouldDeselectItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewDidDeselectItem = [_asyncDelegate respondsToSelector:@selector(collectionView:didDeselectItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewShouldHighlightItem = [_asyncDelegate respondsToSelector:@selector(collectionView:shouldHighlightItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewDidHighlightItem = [_asyncDelegate respondsToSelector:@selector(collectionView:didHighlightItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewDidUnhighlightItem = [_asyncDelegate respondsToSelector:@selector(collectionView:didUnhighlightItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewShouldShowMenuForItem = [_asyncDelegate respondsToSelector:@selector(collectionView:shouldShowMenuForItemAtIndexPath:)];
_asyncDelegateFlags.collectionViewCanPerformActionForItem = [_asyncDelegate respondsToSelector:@selector(collectionView:canPerformAction:forItemAtIndexPath:withSender:)];
_asyncDelegateFlags.collectionViewPerformActionForItem = [_asyncDelegate respondsToSelector:@selector(collectionView:performAction:forItemAtIndexPath:withSender:)];
_asyncDelegateFlags.collectionNodeWillDisplayItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:willDisplayItemWithNode:)];
_asyncDelegateFlags.collectionNodeDidEndDisplayingItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:didEndDisplayingItemWithNode:)];
_asyncDelegateFlags.collectionNodeWillBeginBatchFetch = [_asyncDelegate respondsToSelector:@selector(collectionNode:willBeginBatchFetchWithContext:)];
_asyncDelegateFlags.shouldBatchFetchForCollectionNode = [_asyncDelegate respondsToSelector:@selector(shouldBatchFetchForCollectionNode:)];
_asyncDelegateFlags.collectionNodeShouldSelectItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:shouldSelectItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeDidSelectItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:didSelectItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeShouldDeselectItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:shouldDeselectItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeDidDeselectItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:didDeselectItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeShouldHighlightItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:shouldHighlightItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeDidHighlightItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:didHighlightItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeDidUnhighlightItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:didUnhighlightItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeShouldShowMenuForItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:shouldShowMenuForItemAtIndexPath:)];
_asyncDelegateFlags.collectionNodeCanPerformActionForItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:canPerformAction:forItemAtIndexPath:sender:)];
_asyncDelegateFlags.collectionNodePerformActionForItem = [_asyncDelegate respondsToSelector:@selector(collectionNode:performAction:forItemAtIndexPath:sender:)];
_asyncDelegateFlags.interop = [_asyncDelegate conformsToProtocol:@protocol(ASCollectionDelegateInterop)];
if (_asyncDelegateFlags.interop) {
id<ASCollectionDelegateInterop> interopDelegate = (id<ASCollectionDelegateInterop>)_asyncDelegate;
_asyncDelegateFlags.interopWillDisplayCell = [interopDelegate respondsToSelector:@selector(collectionView:willDisplayCell:forItemAtIndexPath:)];
_asyncDelegateFlags.interopDidEndDisplayingCell = [interopDelegate respondsToSelector:@selector(collectionView:didEndDisplayingCell:forItemAtIndexPath:)];
}
}
super.delegate = (id<UICollectionViewDelegate>)_proxyDelegate;
//Cache results of layoutInspector to ensure flags are up to date if getter lazily loads a new one.
id<ASCollectionViewLayoutInspecting> layoutInspector = self.layoutInspector;
if (_layoutInspectorFlags.didChangeCollectionViewDelegate) {
[layoutInspector didChangeCollectionViewDelegate:asyncDelegate];
}
}
- (void)setCollectionViewLayout:(nonnull UICollectionViewLayout *)collectionViewLayout
{
ASDisplayNodeAssertMainThread();
[super setCollectionViewLayout:collectionViewLayout];
[self _configureCollectionViewLayout:collectionViewLayout];
// Trigger recreation of layout inspector with new collection view layout
if (_layoutInspector != nil) {
_layoutInspector = nil;
[self layoutInspector];
}
}
- (id<ASCollectionViewLayoutInspecting>)layoutInspector
{
if (_layoutInspector == nil) {
UICollectionViewLayout *layout = self.collectionViewLayout;
if (layout == nil) {
// Layout hasn't been set yet, we're still init'ing
return nil;
}
_defaultLayoutInspector = [layout asdk_layoutInspector];
ASDisplayNodeAssertNotNil(_defaultLayoutInspector, @"You must not return nil from -asdk_layoutInspector. Return [super asdk_layoutInspector] if you have to! Layout: %@", layout);
// Explicitly call the setter to wire up the _layoutInspectorFlags
self.layoutInspector = _defaultLayoutInspector;
}
return _layoutInspector;
}
- (void)setLayoutInspector:(id<ASCollectionViewLayoutInspecting>)layoutInspector
{
_layoutInspector = layoutInspector;
_layoutInspectorFlags.constrainedSizeForSupplementaryNodeOfKindAtIndexPath = [_layoutInspector respondsToSelector:@selector(collectionView:constrainedSizeForSupplementaryNodeOfKind:atIndexPath:)];
_layoutInspectorFlags.supplementaryNodesOfKindInSection = [_layoutInspector respondsToSelector:@selector(collectionView:supplementaryNodesOfKind:inSection:)];
_layoutInspectorFlags.didChangeCollectionViewDataSource = [_layoutInspector respondsToSelector:@selector(didChangeCollectionViewDataSource:)];
_layoutInspectorFlags.didChangeCollectionViewDelegate = [_layoutInspector respondsToSelector:@selector(didChangeCollectionViewDelegate:)];
if (_layoutInspectorFlags.didChangeCollectionViewDataSource) {
[_layoutInspector didChangeCollectionViewDataSource:self.asyncDataSource];
}
if (_layoutInspectorFlags.didChangeCollectionViewDelegate) {
[_layoutInspector didChangeCollectionViewDelegate:self.asyncDelegate];
}
}
- (void)setTuningParameters:(ASRangeTuningParameters)tuningParameters forRangeType:(ASLayoutRangeType)rangeType
{
[_rangeController setTuningParameters:tuningParameters forRangeMode:ASLayoutRangeModeFull rangeType:rangeType];
}
- (ASRangeTuningParameters)tuningParametersForRangeType:(ASLayoutRangeType)rangeType
{
return [_rangeController tuningParametersForRangeMode:ASLayoutRangeModeFull rangeType:rangeType];
}
- (void)setTuningParameters:(ASRangeTuningParameters)tuningParameters forRangeMode:(ASLayoutRangeMode)rangeMode rangeType:(ASLayoutRangeType)rangeType
{
[_rangeController setTuningParameters:tuningParameters forRangeMode:rangeMode rangeType:rangeType];
}
- (ASRangeTuningParameters)tuningParametersForRangeMode:(ASLayoutRangeMode)rangeMode rangeType:(ASLayoutRangeType)rangeType
{
return [_rangeController tuningParametersForRangeMode:rangeMode rangeType:rangeType];
}
- (void)setZeroContentInsets:(BOOL)zeroContentInsets
{
_zeroContentInsets = zeroContentInsets;
}
- (BOOL)zeroContentInsets
{
return _zeroContentInsets;
}
/// Uses latest size range from data source and -layoutThatFits:.
- (CGSize)sizeForElement:(ASCollectionElement *)element
{
ASDisplayNodeAssertMainThread();
if (element == nil) {
return CGSizeZero;
}
NSString *supplementaryKind = element.supplementaryElementKind;
NSIndexPath *indexPath = [_dataController.visibleMap indexPathForElement:element];
ASSizeRange sizeRange;
if (supplementaryKind == nil) {
sizeRange = [self dataController:_dataController constrainedSizeForNodeAtIndexPath:indexPath];
} else {
sizeRange = [self dataController:_dataController constrainedSizeForSupplementaryNodeOfKind:supplementaryKind atIndexPath:indexPath];
}
return [element.node layoutThatFits:sizeRange].size;
}
- (CGSize)calculatedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath
{
ASDisplayNodeAssertMainThread();
ASCollectionElement *e = [_dataController.visibleMap elementForItemAtIndexPath:indexPath];
return [self sizeForElement:e];
}
- (ASCellNode *)nodeForItemAtIndexPath:(NSIndexPath *)indexPath
{
return [_dataController.visibleMap elementForItemAtIndexPath:indexPath].node;
}
- (NSIndexPath *)convertIndexPathFromCollectionNode:(NSIndexPath *)indexPath waitingIfNeeded:(BOOL)wait
{
if (indexPath == nil) {
return nil;
}
// If this is a section index path, we don't currently have a method
// to do a mapping.
if (indexPath.item == NSNotFound) {
return indexPath;
} else {
NSIndexPath *viewIndexPath = [_dataController.visibleMap convertIndexPath:indexPath fromMap:_dataController.pendingMap];
if (viewIndexPath == nil && wait) {
[self waitUntilAllUpdatesAreCommitted];
return [self convertIndexPathFromCollectionNode:indexPath waitingIfNeeded:NO];
}
return viewIndexPath;
}
}
/**
* Asserts that the index path is a valid view-index-path, and returns it if so, nil otherwise.
*/
- (nullable NSIndexPath *)validateIndexPath:(nullable NSIndexPath *)indexPath
{
if (indexPath == nil) {
return nil;
}
NSInteger section = indexPath.section;
if (section >= self.numberOfSections) {
ASDisplayNodeFailAssert(@"Collection view index path has invalid section %lu, section count = %lu", (unsigned long)section, (unsigned long)self.numberOfSections);
return nil;
}
NSInteger item = indexPath.item;
// item == NSNotFound means e.g. "scroll to this section" and is acceptable
if (item != NSNotFound && item >= [self numberOfItemsInSection:section]) {
ASDisplayNodeFailAssert(@"Collection view index path has invalid item %lu in section %lu, item count = %lu", (unsigned long)indexPath.item, (unsigned long)section, (unsigned long)[self numberOfItemsInSection:section]);
return nil;
}
return indexPath;
}
- (NSIndexPath *)convertIndexPathToCollectionNode:(NSIndexPath *)indexPath
{
if ([self validateIndexPath:indexPath] == nil) {
return nil;
}
// If this is a section index path, we don't currently have a method
// to do a mapping.
if (indexPath.item == NSNotFound) {
return indexPath;
} else {
return [_dataController.pendingMap convertIndexPath:indexPath fromMap:_dataController.visibleMap];
}
}
- (NSArray<NSIndexPath *> *)convertIndexPathsToCollectionNode:(NSArray<NSIndexPath *> *)indexPaths
{
if (indexPaths == nil) {
return nil;
}
NSMutableArray<NSIndexPath *> *indexPathsArray = [NSMutableArray arrayWithCapacity:indexPaths.count];
for (NSIndexPath *indexPathInView in indexPaths) {
NSIndexPath *indexPath = [self convertIndexPathToCollectionNode:indexPathInView];
if (indexPath != nil) {
[indexPathsArray addObject:indexPath];
}
}
return indexPathsArray;
}
- (ASCellNode *)supplementaryNodeForElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
{
return [_dataController.visibleMap supplementaryElementOfKind:elementKind atIndexPath:indexPath].node;
}
- (NSIndexPath *)indexPathForNode:(ASCellNode *)cellNode
{
return [_dataController.visibleMap indexPathForElement:cellNode.collectionElement];
}
- (NSArray *)visibleNodes
{
NSArray *indexPaths = [self indexPathsForVisibleItems];
NSMutableArray *visibleNodes = [[NSMutableArray alloc] init];
for (NSIndexPath *indexPath in indexPaths) {
ASCellNode *node = [self nodeForItemAtIndexPath:indexPath];
if (node) {
// It is possible for UICollectionView to return indexPaths before the node is completed.
[visibleNodes addObject:node];
}
}
return visibleNodes;
}
#pragma mark Internal
- (void)_configureCollectionViewLayout:(nonnull UICollectionViewLayout *)layout
{
_hasDataControllerLayoutDelegate = [layout conformsToProtocol:@protocol(ASDataControllerLayoutDelegate)];
if (_hasDataControllerLayoutDelegate) {
_dataController.layoutDelegate = (id<ASDataControllerLayoutDelegate>)layout;
}
}
/**
Performing nested batch updates with super (e.g. resizing a cell node & updating collection view during same frame)
can cause super to throw data integrity exceptions because it checks the data source counts before
the update is complete.
Always call [self _superPerform:] rather than [super performBatch:] so that we can keep our `superPerformingBatchUpdates` flag updated.
*/
- (void)_superPerformBatchUpdates:(void(^)())updates completion:(void(^)(BOOL finished))completion
{
ASDisplayNodeAssertMainThread();
_superBatchUpdateCount++;
[super performBatchUpdates:updates completion:completion];
_superBatchUpdateCount--;
}
#pragma mark Assertions.
- (ASDataController *)dataController
{
return _dataController;
}
- (void)beginUpdates
{
ASDisplayNodeAssertMainThread();
// _changeSet must be available during batch update
ASDisplayNodeAssertTrue((_batchUpdateCount > 0) == (_changeSet != nil));
if (_batchUpdateCount == 0) {
_changeSet = [[_ASHierarchyChangeSet alloc] initWithOldData:[_dataController itemCountsFromDataSource]];
}
_batchUpdateCount++;
}
- (void)endUpdatesAnimated:(BOOL)animated completion:(nullable void (^)(BOOL))completion
{
ASDisplayNodeAssertMainThread();
ASDisplayNodeAssertNotNil(_changeSet, @"_changeSet must be available when batch update ends");
_batchUpdateCount--;
// Prevent calling endUpdatesAnimated:completion: in an unbalanced way
NSAssert(_batchUpdateCount >= 0, @"endUpdatesAnimated:completion: called without having a balanced beginUpdates call");
[_changeSet addCompletionHandler:completion];
if (_batchUpdateCount == 0) {
_ASHierarchyChangeSet *changeSet = _changeSet;
// Nil out _changeSet before forwarding to _dataController to allow the change set to cause subsequent batch updates on the same run loop
_changeSet = nil;
changeSet.animated = animated;
[_dataController updateWithChangeSet:changeSet];
}
}
- (void)performBatchAnimated:(BOOL)animated updates:(void (^)())updates completion:(void (^)(BOOL))completion
{
ASDisplayNodeAssertMainThread();
[self beginUpdates];
if (updates) {
updates();
}
[self endUpdatesAnimated:animated completion:completion];
}
- (void)performBatchUpdates:(void (^)())updates completion:(void (^)(BOOL))completion
{
// We capture the current state of whether animations are enabled if they don't provide us with one.
[self performBatchAnimated:[UIView areAnimationsEnabled] updates:updates completion:completion];
}
- (void)registerSupplementaryNodeOfKind:(NSString *)elementKind
{
ASDisplayNodeAssert(elementKind != nil, @"A kind is needed for supplementary node registration");
[_registeredSupplementaryKinds addObject:elementKind];
[self registerClass:[_ASCollectionReusableView class] forSupplementaryViewOfKind:elementKind withReuseIdentifier:kReuseIdentifier];
}
- (void)insertSections:(NSIndexSet *)sections
{
ASDisplayNodeAssertMainThread();
if (sections.count == 0) { return; }
[self performBatchUpdates:^{
[_changeSet insertSections:sections animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (void)deleteSections:(NSIndexSet *)sections
{
ASDisplayNodeAssertMainThread();
if (sections.count == 0) { return; }
[self performBatchUpdates:^{
[_changeSet deleteSections:sections animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (void)reloadSections:(NSIndexSet *)sections
{
ASDisplayNodeAssertMainThread();
if (sections.count == 0) { return; }
[self performBatchUpdates:^{
[_changeSet reloadSections:sections animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (void)moveSection:(NSInteger)section toSection:(NSInteger)newSection
{
ASDisplayNodeAssertMainThread();
[self performBatchUpdates:^{
[_changeSet moveSection:section toSection:newSection animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (id<ASSectionContext>)contextForSection:(NSInteger)section
{
ASDisplayNodeAssertMainThread();
return [_dataController.visibleMap contextForSection:section];
}
- (void)insertItemsAtIndexPaths:(NSArray *)indexPaths
{
ASDisplayNodeAssertMainThread();
if (indexPaths.count == 0) { return; }
[self performBatchUpdates:^{
[_changeSet insertItems:indexPaths animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (void)deleteItemsAtIndexPaths:(NSArray *)indexPaths
{
ASDisplayNodeAssertMainThread();
if (indexPaths.count == 0) { return; }
[self performBatchUpdates:^{
[_changeSet deleteItems:indexPaths animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (void)reloadItemsAtIndexPaths:(NSArray *)indexPaths
{
ASDisplayNodeAssertMainThread();
if (indexPaths.count == 0) { return; }
[self performBatchUpdates:^{
[_changeSet reloadItems:indexPaths animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
- (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath
{
ASDisplayNodeAssertMainThread();
[self performBatchUpdates:^{
[_changeSet moveItemAtIndexPath:indexPath toIndexPath:newIndexPath animationOptions:kASCollectionViewAnimationNone];
} completion:nil];
}
#pragma mark -
#pragma mark Intercepted selectors.
- (NSInteger)numberOfSectionsInCollectionView:(UICollectionView *)collectionView
{
if (_superIsPendingDataLoad) {
[_rangeController setNeedsUpdate];
[self _scheduleCheckForBatchFetchingForNumberOfChanges:1];
_superIsPendingDataLoad = NO;
}
return _dataController.visibleMap.numberOfSections;
}
- (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
{
return [_dataController.visibleMap numberOfItemsInSection:section];
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout sizeForItemAtIndexPath:(NSIndexPath *)indexPath
{
ASDisplayNodeAssertMainThread();
ASCellNode *cell = [self nodeForItemAtIndexPath:indexPath];
if (cell.shouldUseUIKitCell) {
if ([_asyncDelegate respondsToSelector:@selector(collectionView:layout:sizeForItemAtIndexPath:)]) {
CGSize size = [(id)_asyncDelegate collectionView:collectionView layout:collectionViewLayout sizeForItemAtIndexPath:indexPath];
cell.style.preferredSize = size;
return size;
}
}
ASCollectionElement *e = [_dataController.visibleMap elementForItemAtIndexPath:indexPath];
return [self sizeForElement:e];
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)layout referenceSizeForHeaderInSection:(NSInteger)section
{
ASDisplayNodeAssertMainThread();
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:section];
ASCellNode *cell = [self supplementaryNodeForElementKind:UICollectionElementKindSectionHeader
atIndexPath:indexPath];
if (cell.shouldUseUIKitCell && _asyncDelegateFlags.interop) {
if ([_asyncDelegate respondsToSelector:@selector(collectionView:layout:referenceSizeForHeaderInSection:)]) {
return [(id)_asyncDelegate collectionView:collectionView layout:layout referenceSizeForHeaderInSection:section];
}
}
ASCollectionElement *e = [_dataController.visibleMap supplementaryElementOfKind:UICollectionElementKindSectionHeader atIndexPath:indexPath];
return [self sizeForElement:e];
}
- (CGSize)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)layout referenceSizeForFooterInSection:(NSInteger)section
{
ASDisplayNodeAssertMainThread();
NSIndexPath *indexPath = [NSIndexPath indexPathForItem:0 inSection:section];
ASCellNode *cell = [self supplementaryNodeForElementKind:UICollectionElementKindSectionFooter
atIndexPath:indexPath];
if (cell.shouldUseUIKitCell && _asyncDelegateFlags.interop) {
if ([_asyncDelegate respondsToSelector:@selector(collectionView:layout:referenceSizeForFooterInSection:)]) {
return [(id)_asyncDelegate collectionView:collectionView layout:layout referenceSizeForFooterInSection:section];
}
}
ASCollectionElement *e = [_dataController.visibleMap supplementaryElementOfKind:UICollectionElementKindSectionFooter atIndexPath:indexPath];
return [self sizeForElement:e];
}
- (UICollectionReusableView *)collectionView:(UICollectionView *)collectionView viewForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
if ([_registeredSupplementaryKinds containsObject:kind] == NO) {
[self registerSupplementaryNodeOfKind:kind];
}
UICollectionReusableView *view = nil;
ASCellNode *node = [_dataController.visibleMap supplementaryElementOfKind:kind atIndexPath:indexPath].node;
BOOL shouldDequeueExternally = _asyncDataSourceFlags.interopViewForSupplementaryElement && (_asyncDataSourceFlags.interopAlwaysDequeue || node.shouldUseUIKitCell);
if (shouldDequeueExternally) {
// This codepath is used for both IGListKit mode, and app-level UICollectionView interop.
view = [(id<ASCollectionDataSourceInterop>)_asyncDataSource collectionView:collectionView viewForSupplementaryElementOfKind:kind atIndexPath:indexPath];
} else {
ASDisplayNodeAssert(node != nil, @"Supplementary node should exist. Kind = %@, indexPath = %@, collectionDataSource = %@", kind, indexPath, self);
view = [self dequeueReusableSupplementaryViewOfKind:kind withReuseIdentifier:kReuseIdentifier forIndexPath:indexPath];
}
if (_ASCollectionReusableView *reusableView = ASDynamicCast(view, _ASCollectionReusableView)) {
reusableView.node = node;
}
if (node) {
[_rangeController configureContentView:view forCellNode:node];
}
return view;
}
- (UICollectionViewCell *)collectionView:(UICollectionView *)collectionView cellForItemAtIndexPath:(NSIndexPath *)indexPath
{
UICollectionViewCell *cell = nil;
ASCellNode *node = [self nodeForItemAtIndexPath:indexPath];
BOOL shouldDequeueExternally = _asyncDataSourceFlags.interopAlwaysDequeue || (_asyncDataSourceFlags.interop && node.shouldUseUIKitCell);
if (shouldDequeueExternally) {
cell = [(id<ASCollectionDataSourceInterop>)_asyncDataSource collectionView:collectionView cellForItemAtIndexPath:indexPath];
} else {
cell = [self dequeueReusableCellWithReuseIdentifier:kReuseIdentifier forIndexPath:indexPath];
}
ASDisplayNodeAssert(node != nil, @"Cell node should exist. indexPath = %@, collectionDataSource = %@", indexPath, self);
if (_ASCollectionViewCell *asCell = ASDynamicCast(cell, _ASCollectionViewCell)) {
asCell.node = node;
[_rangeController configureContentView:cell.contentView forCellNode:node];
}
return cell;
}
- (void)collectionView:(UICollectionView *)collectionView willDisplayCell:(_ASCollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.interopWillDisplayCell) {
[(id <ASCollectionDelegateInterop>)_asyncDelegate collectionView:collectionView willDisplayCell:cell forItemAtIndexPath:indexPath];
}
// Since _ASCollectionViewCell is not available for subclassing, this is faster than isKindOfClass:
// We must exit early here, because only _ASCollectionViewCell implements the -node accessor method.
if ([cell class] != [_ASCollectionViewCell class]) {
[_rangeController setNeedsUpdate];
return;
}
ASCellNode *cellNode = [cell node];
cellNode.scrollView = collectionView;
// Update the selected background view in collectionView:willDisplayCell:forItemAtIndexPath: otherwise it could be to
// early e.g. if the selectedBackgroundView was set in didLoad()
cell.selectedBackgroundView = cellNode.selectedBackgroundView;
// Under iOS 10+, cells may be removed/re-added to the collection view without
// receiving prepareForReuse/applyLayoutAttributes, as an optimization for e.g.
// if the user is scrolling back and forth across a small set of items.
// In this case, we have to fetch the layout attributes manually.
// This may be possible under iOS < 10 but it has not been observed yet.
if (cell.layoutAttributes == nil) {
cell.layoutAttributes = [collectionView layoutAttributesForItemAtIndexPath:indexPath];
}
ASDisplayNodeAssertNotNil(cellNode, @"Expected node associated with cell that will be displayed not to be nil. indexPath: %@", indexPath);
if (_asyncDelegateFlags.collectionNodeWillDisplayItem && self.collectionNode != nil) {
[_asyncDelegate collectionNode:self.collectionNode willDisplayItemWithNode:cellNode];
} else if (_asyncDelegateFlags.collectionViewWillDisplayNodeForItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self willDisplayNode:cellNode forItemAtIndexPath:indexPath];
} else if (_asyncDelegateFlags.collectionViewWillDisplayNodeForItemDeprecated) {
[_asyncDelegate collectionView:self willDisplayNodeForItemAtIndexPath:indexPath];
}
#pragma clang diagnostic pop
[_rangeController setNeedsUpdate];
if (ASSubclassOverridesSelector([ASCellNode class], [cellNode class], @selector(cellNodeVisibilityEvent:inScrollView:withCellFrame:))) {
[_cellsForVisibilityUpdates addObject:cell];
}
}
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingCell:(_ASCollectionViewCell *)cell forItemAtIndexPath:(NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.interopDidEndDisplayingCell) {
[(id <ASCollectionDelegateInterop>)_asyncDelegate collectionView:collectionView didEndDisplayingCell:cell forItemAtIndexPath:indexPath];
}
// Since _ASCollectionViewCell is not available for subclassing, this is faster than isKindOfClass:
// We must exit early here, because only _ASCollectionViewCell implements the -node accessor method.
if ([cell class] != [_ASCollectionViewCell class]) {
[_rangeController setNeedsUpdate];
return;
}
ASCellNode *cellNode = [cell node];
ASDisplayNodeAssertNotNil(cellNode, @"Expected node associated with removed cell not to be nil.");
if (_asyncDelegateFlags.collectionNodeDidEndDisplayingItem) {
if (ASCollectionNode *collectionNode = self.collectionNode) {
[_asyncDelegate collectionNode:collectionNode didEndDisplayingItemWithNode:cellNode];
}
} else if (_asyncDelegateFlags.collectionViewDidEndDisplayingNodeForItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self didEndDisplayingNode:cellNode forItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
[_rangeController setNeedsUpdate];
[_cellsForVisibilityUpdates removeObject:cell];
cellNode.scrollView = nil;
cell.layoutAttributes = nil;
}
- (void)collectionView:(UICollectionView *)collectionView willDisplaySupplementaryView:(_ASCollectionReusableView *)view forElementKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
{
// This is a safeguard similar to the behavior for cells in -[ASCollectionView collectionView:willDisplayCell:forItemAtIndexPath:]
// It ensures _ASCollectionReusableView receives layoutAttributes and calls applyLayoutAttributes.
if (view.layoutAttributes == nil) {
view.layoutAttributes = [collectionView layoutAttributesForSupplementaryElementOfKind:elementKind atIndexPath:indexPath];
}
if (_asyncDelegateFlags.collectionNodeWillDisplaySupplementaryElement) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
ASCellNode *node = [self supplementaryNodeForElementKind:elementKind atIndexPath:indexPath];
ASDisplayNodeAssert([node.supplementaryElementKind isEqualToString:elementKind], @"Expected node for supplementary element to have kind '%@', got '%@'.", elementKind, node.supplementaryElementKind);
[_asyncDelegate collectionNode:collectionNode willDisplaySupplementaryElementWithNode:node];
}
}
- (void)collectionView:(UICollectionView *)collectionView didEndDisplayingSupplementaryView:(UICollectionReusableView *)view forElementOfKind:(NSString *)elementKind atIndexPath:(NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeDidEndDisplayingSupplementaryElement) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
ASCellNode *node = [self supplementaryNodeForElementKind:elementKind atIndexPath:indexPath];
ASDisplayNodeAssert([node.supplementaryElementKind isEqualToString:elementKind], @"Expected node for supplementary element to have kind '%@', got '%@'.", elementKind, node.supplementaryElementKind);
[_asyncDelegate collectionNode:collectionNode didEndDisplayingSupplementaryElementWithNode:node];
}
}
- (BOOL)collectionView:(UICollectionView *)collectionView shouldSelectItemAtIndexPath:(NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeShouldSelectItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, NO);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
return [_asyncDelegate collectionNode:collectionNode shouldSelectItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewShouldSelectItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDelegate collectionView:self shouldSelectItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
return YES;
}
- (void)collectionView:(UICollectionView *)collectionView didSelectItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeDidSelectItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
[_asyncDelegate collectionNode:collectionNode didSelectItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewDidSelectItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self didSelectItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
}
- (BOOL)collectionView:(UICollectionView *)collectionView shouldDeselectItemAtIndexPath:(NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeShouldDeselectItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, NO);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
return [_asyncDelegate collectionNode:collectionNode shouldDeselectItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewShouldDeselectItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDelegate collectionView:self shouldDeselectItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
return YES;
}
- (void)collectionView:(UICollectionView *)collectionView didDeselectItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeDidDeselectItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
[_asyncDelegate collectionNode:collectionNode didDeselectItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewDidDeselectItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self didDeselectItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
}
- (BOOL)collectionView:(UICollectionView *)collectionView shouldHighlightItemAtIndexPath:(NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeShouldHighlightItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, NO);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
return [_asyncDelegate collectionNode:collectionNode shouldHighlightItemAtIndexPath:indexPath];
} else {
return YES;
}
} else if (_asyncDelegateFlags.collectionViewShouldHighlightItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDelegate collectionView:self shouldHighlightItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
return YES;
}
- (void)collectionView:(UICollectionView *)collectionView didHighlightItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeDidHighlightItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
[_asyncDelegate collectionNode:collectionNode didHighlightItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewDidHighlightItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self didHighlightItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
}
- (void)collectionView:(UICollectionView *)collectionView didUnhighlightItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeDidUnhighlightItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
[_asyncDelegate collectionNode:collectionNode didUnhighlightItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewDidUnhighlightItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self didUnhighlightItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
}
- (BOOL)collectionView:(UICollectionView *)collectionView shouldShowMenuForItemAtIndexPath:(nonnull NSIndexPath *)indexPath
{
if (_asyncDelegateFlags.collectionNodeShouldShowMenuForItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, NO);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
return [_asyncDelegate collectionNode:collectionNode shouldShowMenuForItemAtIndexPath:indexPath];
}
} else if (_asyncDelegateFlags.collectionViewShouldShowMenuForItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDelegate collectionView:self shouldShowMenuForItemAtIndexPath:indexPath];
#pragma clang diagnostic pop
}
return NO;
}
- (BOOL)collectionView:(UICollectionView *)collectionView canPerformAction:(nonnull SEL)action forItemAtIndexPath:(nonnull NSIndexPath *)indexPath withSender:(nullable id)sender
{
if (_asyncDelegateFlags.collectionNodeCanPerformActionForItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, NO);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
return [_asyncDelegate collectionNode:collectionNode canPerformAction:action forItemAtIndexPath:indexPath sender:sender];
}
} else if (_asyncDelegateFlags.collectionViewCanPerformActionForItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDelegate collectionView:self canPerformAction:action forItemAtIndexPath:indexPath withSender:sender];
#pragma clang diagnostic pop
}
return NO;
}
- (void)collectionView:(UICollectionView *)collectionView performAction:(nonnull SEL)action forItemAtIndexPath:(nonnull NSIndexPath *)indexPath withSender:(nullable id)sender
{
if (_asyncDelegateFlags.collectionNodePerformActionForItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
indexPath = [self convertIndexPathToCollectionNode:indexPath];
if (indexPath != nil) {
[_asyncDelegate collectionNode:collectionNode performAction:action forItemAtIndexPath:indexPath sender:sender];
}
} else if (_asyncDelegateFlags.collectionViewPerformActionForItem) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self performAction:action forItemAtIndexPath:indexPath withSender:sender];
#pragma clang diagnostic pop
}
}
- (void)scrollViewDidScroll:(UIScrollView *)scrollView
{
// If a scroll happenes the current range mode needs to go to full
ASInterfaceState interfaceState = [self interfaceStateForRangeController:_rangeController];
if (ASInterfaceStateIncludesVisible(interfaceState)) {
[_rangeController updateCurrentRangeWithMode:ASLayoutRangeModeFull];
[self _checkForBatchFetching];
}
for (_ASCollectionViewCell *collectionCell in _cellsForVisibilityUpdates) {
// Only nodes that respond to the selector are added to _cellsForVisibilityUpdates
[[collectionCell node] cellNodeVisibilityEvent:ASCellNodeVisibilityEventVisibleRectChanged
inScrollView:scrollView
withCellFrame:collectionCell.frame];
}
if (_asyncDelegateFlags.scrollViewDidScroll) {
[_asyncDelegate scrollViewDidScroll:scrollView];
}
}
- (void)scrollViewWillEndDragging:(UIScrollView *)scrollView withVelocity:(CGPoint)velocity targetContentOffset:(inout CGPoint *)targetContentOffset
{
CGPoint contentOffset = scrollView.contentOffset;
_deceleratingVelocity = CGPointMake(
contentOffset.x - ((targetContentOffset != NULL) ? targetContentOffset->x : 0),
contentOffset.y - ((targetContentOffset != NULL) ? targetContentOffset->y : 0)
);
if (targetContentOffset != NULL) {
ASDisplayNodeAssert(_batchContext != nil, @"Batch context should exist");
[self _beginBatchFetchingIfNeededWithContentOffset:*targetContentOffset];
}
if (_asyncDelegateFlags.scrollViewWillEndDragging) {
[_asyncDelegate scrollViewWillEndDragging:scrollView withVelocity:velocity targetContentOffset:(targetContentOffset ? : &contentOffset)];
}
}
- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
_deceleratingVelocity = CGPointZero;
if (_asyncDelegateFlags.scrollViewDidEndDecelerating) {
[_asyncDelegate scrollViewDidEndDecelerating:scrollView];
}
}
- (void)scrollViewWillBeginDragging:(UIScrollView *)scrollView
{
for (_ASCollectionViewCell *collectionCell in _cellsForVisibilityUpdates) {
[[collectionCell node] cellNodeVisibilityEvent:ASCellNodeVisibilityEventWillBeginDragging
inScrollView:scrollView
withCellFrame:collectionCell.frame];
}
if (_asyncDelegateFlags.scrollViewWillBeginDragging) {
[_asyncDelegate scrollViewWillBeginDragging:scrollView];
}
}
- (void)scrollViewDidEndDragging:(UIScrollView *)scrollView willDecelerate:(BOOL)decelerate
{
for (_ASCollectionViewCell *collectionCell in _cellsForVisibilityUpdates) {
[[collectionCell node] cellNodeVisibilityEvent:ASCellNodeVisibilityEventDidEndDragging
inScrollView:scrollView
withCellFrame:collectionCell.frame];
}
if (_asyncDelegateFlags.scrollViewDidEndDragging) {
[_asyncDelegate scrollViewDidEndDragging:scrollView willDecelerate:decelerate];
}
}
#pragma mark - Scroll Direction.
- (BOOL)inverted
{
return _inverted;
}
- (void)setInverted:(BOOL)inverted
{
_inverted = inverted;
}
- (void)setLeadingScreensForBatching:(CGFloat)leadingScreensForBatching
{
_leadingScreensForBatching = leadingScreensForBatching;
}
- (CGFloat)leadingScreensForBatching
{
return _leadingScreensForBatching;
}
- (ASScrollDirection)scrollDirection
{
CGPoint scrollVelocity;
if (self.isTracking) {
scrollVelocity = [self.panGestureRecognizer velocityInView:self.superview];
} else {
scrollVelocity = _deceleratingVelocity;
}
ASScrollDirection scrollDirection = [self _scrollDirectionForVelocity:scrollVelocity];
return ASScrollDirectionApplyTransform(scrollDirection, self.transform);
}
- (ASScrollDirection)_scrollDirectionForVelocity:(CGPoint)scrollVelocity
{
ASScrollDirection direction = ASScrollDirectionNone;
ASScrollDirection scrollableDirections = [self scrollableDirections];
if (ASScrollDirectionContainsHorizontalDirection(scrollableDirections)) { // Can scroll horizontally.
if (scrollVelocity.x < 0.0) {
direction |= ASScrollDirectionRight;
} else if (scrollVelocity.x > 0.0) {
direction |= ASScrollDirectionLeft;
}
}
if (ASScrollDirectionContainsVerticalDirection(scrollableDirections)) { // Can scroll vertically.
if (scrollVelocity.y < 0.0) {
direction |= ASScrollDirectionDown;
} else if (scrollVelocity.y > 0.0) {
direction |= ASScrollDirectionUp;
}
}
return direction;
}
- (ASScrollDirection)scrollableDirections
{
ASDisplayNodeAssertNotNil(self.layoutInspector, @"Layout inspector should be assigned.");
return [self.layoutInspector scrollableDirections];
}
- (ASScrollDirection)flowLayoutScrollableDirections:(UICollectionViewFlowLayout *)flowLayout {
return (flowLayout.scrollDirection == UICollectionViewScrollDirectionHorizontal) ? ASScrollDirectionHorizontalDirections : ASScrollDirectionVerticalDirections;
}
- (void)layoutSubviews
{
if (_cellsForLayoutUpdates.count > 0) {
NSMutableArray<ASCellNode *> *nodesSizesChanged = [NSMutableArray array];
[_dataController relayoutNodes:_cellsForLayoutUpdates nodesSizeChanged:nodesSizesChanged];
[self nodesDidRelayout:nodesSizesChanged];
}
[_cellsForLayoutUpdates removeAllObjects];
// Flush any pending invalidation action if needed.
ASCollectionViewInvalidationStyle invalidationStyle = _nextLayoutInvalidationStyle;
_nextLayoutInvalidationStyle = ASCollectionViewInvalidationStyleNone;
switch (invalidationStyle) {
case ASCollectionViewInvalidationStyleWithAnimation:
if (0 == _superBatchUpdateCount) {
[self _superPerformBatchUpdates:^{ } completion:nil];
}
break;
case ASCollectionViewInvalidationStyleWithoutAnimation:
[self.collectionViewLayout invalidateLayout];
break;
default:
break;
}
// To ensure _maxSizeForNodesConstrainedSize is up-to-date for every usage, this call to super must be done last
[super layoutSubviews];
if (_zeroContentInsets) {
self.contentInset = UIEdgeInsetsZero;
}
// Update range controller immediately if possible & needed.
// Calling -updateIfNeeded in here with self.window == nil (early in the collection view's life)
// may cause UICollectionView data related crashes. We'll update in -didMoveToWindow anyway.
if (self.window != nil) {
[_rangeController updateIfNeeded];
}
}
#pragma mark - Batch Fetching
- (ASBatchContext *)batchContext
{
return _batchContext;
}
- (BOOL)canBatchFetch
{
// if the delegate does not respond to this method, there is no point in starting to fetch
BOOL canFetch = _asyncDelegateFlags.collectionNodeWillBeginBatchFetch || _asyncDelegateFlags.collectionViewWillBeginBatchFetch;
if (canFetch && _asyncDelegateFlags.shouldBatchFetchForCollectionNode) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, NO);
return [_asyncDelegate shouldBatchFetchForCollectionNode:collectionNode];
} else if (canFetch && _asyncDelegateFlags.shouldBatchFetchForCollectionView) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDelegate shouldBatchFetchForCollectionView:self];
#pragma clang diagnostic pop
} else {
return canFetch;
}
}
- (void)_scheduleCheckForBatchFetchingForNumberOfChanges:(NSUInteger)changes
{
// Prevent fetching will continually trigger in a loop after reaching end of content and no new content was provided
if (changes == 0 && _hasEverCheckedForBatchFetchingDueToUpdate) {
return;
}
_hasEverCheckedForBatchFetchingDueToUpdate = YES;
// Push this to the next runloop to be sure the scroll view has the right content size
dispatch_async(dispatch_get_main_queue(), ^{
[self _checkForBatchFetching];
});
}
- (void)_checkForBatchFetching
{
// Dragging will be handled in scrollViewWillEndDragging:withVelocity:targetContentOffset:
if (self.isDragging || self.isTracking) {
return;
}
[self _beginBatchFetchingIfNeededWithContentOffset:self.contentOffset];
}
- (void)_beginBatchFetchingIfNeededWithContentOffset:(CGPoint)contentOffset
{
if (ASDisplayShouldFetchBatchForScrollView(self, self.scrollDirection, self.scrollableDirections, contentOffset)) {
[self _beginBatchFetching];
}
}
- (void)_beginBatchFetching
{
[_batchContext beginBatchFetching];
if (_asyncDelegateFlags.collectionNodeWillBeginBatchFetch) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
GET_COLLECTIONNODE_OR_RETURN(collectionNode, (void)0);
[_asyncDelegate collectionNode:collectionNode willBeginBatchFetchWithContext:_batchContext];
});
} else if (_asyncDelegateFlags.collectionViewWillBeginBatchFetch) {
dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^{
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
[_asyncDelegate collectionView:self willBeginBatchFetchWithContext:_batchContext];
#pragma clang diagnostic pop
});
}
}
#pragma mark - ASDataControllerSource
- (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAtIndexPath:(NSIndexPath *)indexPath
{
ASCellNodeBlock block = nil;
ASCellNode *cell = nil;
if (_asyncDataSourceFlags.collectionNodeNodeBlockForItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, ^{ return [[ASCellNode alloc] init]; });
block = [_asyncDataSource collectionNode:collectionNode nodeBlockForItemAtIndexPath:indexPath];
} else if (_asyncDataSourceFlags.collectionNodeNodeForItem) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, ^{ return [[ASCellNode alloc] init]; });
cell = [_asyncDataSource collectionNode:collectionNode nodeForItemAtIndexPath:indexPath];
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
} else if (_asyncDataSourceFlags.collectionViewNodeBlockForItem) {
block = [_asyncDataSource collectionView:self nodeBlockForItemAtIndexPath:indexPath];
} else if (_asyncDataSourceFlags.collectionViewNodeForItem) {
cell = [_asyncDataSource collectionView:self nodeForItemAtIndexPath:indexPath];
}
#pragma clang diagnostic pop
// Handle nil node block or cell
if (cell && [cell isKindOfClass:[ASCellNode class]]) {
block = ^{
return cell;
};
}
if (block == nil) {
if (_asyncDataSourceFlags.interop) {
block = ^{
ASCellNode *cell = [[ASCellNode alloc] init];
cell.shouldUseUIKitCell = YES;
cell.style.preferredSize = CGSizeZero;
return cell;
};
} else {
ASDisplayNodeFailAssert(@"ASCollection could not get a node block for row at index path %@: %@, %@. If you are trying to display a UICollectionViewCell, make sure your dataSource conforms to the <ASCollectionDataSourceInterop> protocol!", indexPath, cell, block);
block = ^{
return [[ASCellNode alloc] init];
};
}
}
// Wrap the node block
__weak __typeof__(self) weakSelf = self;
return ^{
__typeof__(self) strongSelf = weakSelf;
ASCellNode *node = (block != nil ? block() : [[ASCellNode alloc] init]);
[node enterHierarchyState:ASHierarchyStateRangeManaged];
if (node.interactionDelegate == nil) {
node.interactionDelegate = strongSelf;
}
if (_inverted) {
node.transform = CATransform3DMakeScale(1, -1, 1) ;
}
return node;
};
return block;
}
- (NSUInteger)dataController:(ASDataController *)dataController rowsInSection:(NSUInteger)section
{
if (_asyncDataSourceFlags.collectionNodeNumberOfItemsInSection) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, 0);
return [_asyncDataSource collectionNode:collectionNode numberOfItemsInSection:section];
} else if (_asyncDataSourceFlags.collectionViewNumberOfItemsInSection) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDataSource collectionView:self numberOfItemsInSection:section];
#pragma clang diagnostic pop
} else {
return 0;
}
}
- (NSUInteger)numberOfSectionsInDataController:(ASDataController *)dataController {
if (_asyncDataSourceFlags.numberOfSectionsInCollectionNode) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, 0);
return [_asyncDataSource numberOfSectionsInCollectionNode:collectionNode];
} else if (_asyncDataSourceFlags.numberOfSectionsInCollectionView) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
return [_asyncDataSource numberOfSectionsInCollectionView:self];
#pragma clang diagnostic pop
} else {
return 1;
}
}
- (BOOL)dataController:(ASDataController *)dataController presentedSizeForElement:(ASCollectionElement *)element matchesSize:(CGSize)size
{
NSIndexPath *indexPath = [self indexPathForNode:element.node];
UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:indexPath];
CGRect rect = attributes.frame;
return CGSizeEqualToSizeWithIn(rect.size, size, FLT_EPSILON);
}
#pragma mark - ASDataControllerSource optional methods
- (ASCellNodeBlock)dataController:(ASDataController *)dataController supplementaryNodeBlockOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
ASCellNodeBlock nodeBlock = nil;
ASCellNode *node = nil;
if (_asyncDataSourceFlags.collectionNodeNodeBlockForSupplementaryElement) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, ^{ return [[ASCellNode alloc] init]; });
nodeBlock = [_asyncDataSource collectionNode:collectionNode nodeBlockForSupplementaryElementOfKind:kind atIndexPath:indexPath];
} else if (_asyncDataSourceFlags.collectionNodeNodeForSupplementaryElement) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, ^{ return [[ASCellNode alloc] init]; });
node = [_asyncDataSource collectionNode:collectionNode nodeForSupplementaryElementOfKind:kind atIndexPath:indexPath];
} else if (_asyncDataSourceFlags.collectionViewNodeForSupplementaryElement) {
#pragma clang diagnostic push
#pragma clang diagnostic ignored "-Wdeprecated-declarations"
node = [_asyncDataSource collectionView:self nodeForSupplementaryElementOfKind:kind atIndexPath:indexPath];
#pragma clang diagnostic pop
}
if (nodeBlock == nil) {
if (node) {
nodeBlock = ^{ return node; };
} else {
BOOL useUIKitCell = _asyncDataSourceFlags.interop;
nodeBlock = ^{
ASCellNode *node = [[ASCellNode alloc] init];
node.shouldUseUIKitCell = useUIKitCell;
return node;
};
}
}
return nodeBlock;
}
- (NSArray<NSString *> *)dataController:(ASDataController *)dataController supplementaryNodeKindsInSections:(NSIndexSet *)sections
{
if (_asyncDataSourceFlags.collectionNodeSupplementaryElementKindsInSection) {
NSMutableSet *kinds = [NSMutableSet set];
GET_COLLECTIONNODE_OR_RETURN(collectionNode, @[]);
[sections enumerateIndexesUsingBlock:^(NSUInteger section, BOOL * _Nonnull stop) {
NSArray<NSString *> *kindsForSection = [_asyncDataSource collectionNode:collectionNode supplementaryElementKindsInSection:section];
[kinds addObjectsFromArray:kindsForSection];
}];
return [kinds allObjects];
} else {
// TODO: Lock this
return [_registeredSupplementaryKinds allObjects];
}
}
- (ASSizeRange)dataController:(ASDataController *)dataController constrainedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath
{
return [self.layoutInspector collectionView:self constrainedSizeForNodeAtIndexPath:indexPath];
}
- (ASSizeRange)dataController:(ASDataController *)dataController constrainedSizeForSupplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath
{
if (_layoutInspectorFlags.constrainedSizeForSupplementaryNodeOfKindAtIndexPath) {
return [self.layoutInspector collectionView:self constrainedSizeForSupplementaryNodeOfKind:kind atIndexPath:indexPath];
}
ASDisplayNodeAssert(NO, @"To support supplementary nodes in ASCollectionView, it must have a layoutInspector for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
return ASSizeRangeMake(CGSizeZero, CGSizeZero);
}
- (NSUInteger)dataController:(ASDataController *)dataController supplementaryNodesOfKind:(NSString *)kind inSection:(NSUInteger)section
{
if (_asyncDataSource == nil) {
return 0;
}
if (_layoutInspectorFlags.supplementaryNodesOfKindInSection) {
return [self.layoutInspector collectionView:self supplementaryNodesOfKind:kind inSection:section];
}
ASDisplayNodeAssert(NO, @"To support supplementary nodes in ASCollectionView, it must have a layoutInspector for layout inspection. (See ASCollectionViewFlowLayoutInspector for an example.)");
return 0;
}
- (id<ASSectionContext>)dataController:(ASDataController *)dataController contextForSection:(NSInteger)section
{
ASDisplayNodeAssertMainThread();
id<ASSectionContext> context = nil;
if (_asyncDataSourceFlags.collectionNodeContextForSection) {
GET_COLLECTIONNODE_OR_RETURN(collectionNode, nil);
context = [_asyncDataSource collectionNode:collectionNode contextForSection:section];
}
if (context != nil) {
context.collectionView = self;
}
return context;
}
#pragma mark - ASRangeControllerDataSource
- (ASRangeController *)rangeController
{
return _rangeController;
}
/// The UIKit version of this method is only available on iOS >= 9
- (NSArray<NSIndexPath *> *)asdk_indexPathsForVisibleSupplementaryElementsOfKind:(NSString *)kind
{
if (NSFoundationVersionNumber >= NSFoundationVersionNumber_iOS_9_0) {
return [self indexPathsForVisibleSupplementaryElementsOfKind:kind];
}
// iOS 8 workaround
// We cannot use willDisplaySupplementaryView/didEndDisplayingSupplementaryView
// because those methods send index paths for _deleted items_ (invalid index paths)
[self layoutIfNeeded];
NSArray<UICollectionViewLayoutAttributes *> *visibleAttributes = [self.collectionViewLayout layoutAttributesForElementsInRect:self.bounds];
NSMutableArray *result = [NSMutableArray array];
for (UICollectionViewLayoutAttributes *attributes in visibleAttributes) {
if (attributes.representedElementCategory == UICollectionElementCategorySupplementaryView
&& [attributes.representedElementKind isEqualToString:kind]) {
[result addObject:attributes.indexPath];
}
}
return result;
}
- (NSArray<ASCollectionElement *> *)visibleElementsForRangeController:(ASRangeController *)rangeController
{
if (CGRectIsEmpty(self.bounds)) {
return @[];
}
ASElementMap *map = _dataController.visibleMap;
NSMutableArray<ASCollectionElement *> *result = [NSMutableArray array];
// Visible items
for (NSIndexPath *indexPath in self.indexPathsForVisibleItems) {
ASCollectionElement *element = [map elementForItemAtIndexPath:indexPath];
if (element != nil) {
[result addObject:element];
} else {
ASDisplayNodeFailAssert(@"Couldn't find 'visible' item at index path %@ in map %@", indexPath, map);
}
}
// Visible supplementary elements
for (NSString *kind in map.supplementaryElementKinds) {
for (NSIndexPath *indexPath in [self asdk_indexPathsForVisibleSupplementaryElementsOfKind:kind]) {
ASCollectionElement *element = [map supplementaryElementOfKind:kind atIndexPath:indexPath];
if (element != nil) {
[result addObject:element];
} else {
ASDisplayNodeFailAssert(@"Couldn't find 'visible' supplementary element of kind %@ at index path %@ in map %@", kind, indexPath, map);
}
}
}
return result;
}
- (ASElementMap *)elementMapForRangeController:(ASRangeController *)rangeController
{
return _dataController.visibleMap;
}
- (ASScrollDirection)scrollDirectionForRangeController:(ASRangeController *)rangeController
{
return self.scrollDirection;
}
- (ASInterfaceState)interfaceStateForRangeController:(ASRangeController *)rangeController
{
return ASInterfaceStateForDisplayNode(self.collectionNode, self.window);
}
- (NSString *)nameForRangeControllerDataSource
{
return self.asyncDataSource ? NSStringFromClass([self.asyncDataSource class]) : NSStringFromClass([self class]);
}
#pragma mark - ASRangeControllerDelegate
- (void)rangeController:(ASRangeController *)rangeController willUpdateWithChangeSet:(_ASHierarchyChangeSet *)changeSet
{
ASDisplayNodeAssertMainThread();
if (!self.asyncDataSource || _superIsPendingDataLoad) {
return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes
}
if (changeSet.includesReloadData) {
//TODO Do we need to notify _layoutFacilitator?
return;
}
for (_ASHierarchyItemChange *change in [changeSet itemChangesOfType:_ASHierarchyChangeTypeDelete]) {
[_layoutFacilitator collectionViewWillEditCellsAtIndexPaths:change.indexPaths batched:YES];
}
for (_ASHierarchySectionChange *change in [changeSet sectionChangesOfType:_ASHierarchyChangeTypeDelete]) {
[_layoutFacilitator collectionViewWillEditSectionsAtIndexSet:change.indexSet batched:YES];
}
for (_ASHierarchySectionChange *change in [changeSet sectionChangesOfType:_ASHierarchyChangeTypeInsert]) {
[_layoutFacilitator collectionViewWillEditSectionsAtIndexSet:change.indexSet batched:YES];
}
for (_ASHierarchyItemChange *change in [changeSet itemChangesOfType:_ASHierarchyChangeTypeInsert]) {
[_layoutFacilitator collectionViewWillEditCellsAtIndexPaths:change.indexPaths batched:YES];
}
}
- (void)rangeController:(ASRangeController *)rangeController didUpdateWithChangeSet:(_ASHierarchyChangeSet *)changeSet
{
ASDisplayNodeAssertMainThread();
if (!self.asyncDataSource || _superIsPendingDataLoad) {
[changeSet executeCompletionHandlerWithFinished:NO];
return; // if the asyncDataSource has become invalid while we are processing, ignore this request to avoid crashes
}
ASPerformBlockWithoutAnimation(!changeSet.animated, ^{
if(changeSet.includesReloadData) {
_superIsPendingDataLoad = YES;
[super reloadData];
[changeSet executeCompletionHandlerWithFinished:YES];
} else {
[_layoutFacilitator collectionViewWillPerformBatchUpdates];
__block NSUInteger numberOfUpdates = 0;
[self _superPerformBatchUpdates:^{
for (_ASHierarchyItemChange *change in [changeSet itemChangesOfType:_ASHierarchyChangeTypeReload]) {
[super reloadItemsAtIndexPaths:change.indexPaths];
numberOfUpdates++;
}
for (_ASHierarchySectionChange *change in [changeSet sectionChangesOfType:_ASHierarchyChangeTypeReload]) {
[super reloadSections:change.indexSet];
numberOfUpdates++;
}
for (_ASHierarchyItemChange *change in [changeSet itemChangesOfType:_ASHierarchyChangeTypeOriginalDelete]) {
[super deleteItemsAtIndexPaths:change.indexPaths];
numberOfUpdates++;
}
for (_ASHierarchySectionChange *change in [changeSet sectionChangesOfType:_ASHierarchyChangeTypeOriginalDelete]) {
[super deleteSections:change.indexSet];
numberOfUpdates++;
}
for (_ASHierarchySectionChange *change in [changeSet sectionChangesOfType:_ASHierarchyChangeTypeOriginalInsert]) {
[super insertSections:change.indexSet];
numberOfUpdates++;
}
for (_ASHierarchyItemChange *change in [changeSet itemChangesOfType:_ASHierarchyChangeTypeOriginalInsert]) {
[super insertItemsAtIndexPaths:change.indexPaths];
numberOfUpdates++;
}
} completion:^(BOOL finished){
// Flush any range changes that happened as part of the update animations ending.
[_rangeController updateIfNeeded];
[self _scheduleCheckForBatchFetchingForNumberOfChanges:numberOfUpdates];
[changeSet executeCompletionHandlerWithFinished:finished];
}];
// Flush any range changes that happened as part of submitting the update.
[_rangeController updateIfNeeded];
}
});
}
#pragma mark - ASCellNodeDelegate
- (void)nodeSelectedStateDidChange:(ASCellNode *)node
{
NSIndexPath *indexPath = [self indexPathForNode:node];
if (indexPath) {
if (node.isSelected) {
[super selectItemAtIndexPath:indexPath animated:NO scrollPosition:UICollectionViewScrollPositionNone];
} else {
[super deselectItemAtIndexPath:indexPath animated:NO];
}
}
}
- (void)nodeHighlightedStateDidChange:(ASCellNode *)node
{
NSIndexPath *indexPath = [self indexPathForNode:node];
if (indexPath) {
[self cellForItemAtIndexPath:indexPath].highlighted = node.isHighlighted;
}
}
- (void)nodeDidInvalidateSize:(ASCellNode *)node
{
[_cellsForLayoutUpdates addObject:node];
[self setNeedsLayout];
}
- (void)nodeDidRelayout:(ASCellNode *)node sizeChanged:(BOOL)sizeChanged
{
ASDisplayNodeAssertMainThread();
if (!sizeChanged) {
return;
}
[self nodesDidRelayout:@[node]];
}
- (void)nodesDidRelayout:(NSArray<ASCellNode *> *)nodes
{
ASDisplayNodeAssertMainThread();
if (nodes.count == 0) {
return;
}
NSMutableArray<NSIndexPath *> *uikitIndexPaths = [NSMutableArray arrayWithCapacity:nodes.count];
for (ASCellNode *node in nodes) {
NSIndexPath *uikitIndexPath = [self indexPathForNode:node];
if (uikitIndexPath != nil) {
[uikitIndexPaths addObject:uikitIndexPath];
}
}
[_layoutFacilitator collectionViewWillEditCellsAtIndexPaths:uikitIndexPaths batched:NO];
ASCollectionViewInvalidationStyle invalidationStyle = _nextLayoutInvalidationStyle;
for (ASCellNode *node in nodes) {
if (invalidationStyle == ASCollectionViewInvalidationStyleNone) {
// We nodesDidRelayout also while we are in layoutSubviews. This should be no problem as CA will ignore this
// call while be in a layout pass
[self setNeedsLayout];
invalidationStyle = ASCollectionViewInvalidationStyleWithAnimation;
}
// If we think we're going to animate, check if this node will prevent it.
if (invalidationStyle == ASCollectionViewInvalidationStyleWithAnimation) {
// TODO: Incorporate `shouldAnimateSizeChanges` into ASEnvironmentState for performance benefit.
static dispatch_once_t onceToken;
static BOOL (^shouldNotAnimateBlock)(ASDisplayNode *);
dispatch_once(&onceToken, ^{
shouldNotAnimateBlock = ^BOOL(ASDisplayNode * _Nonnull node) {
return (node.shouldAnimateSizeChanges == NO);
};
});
if (ASDisplayNodeFindFirstNode(node, shouldNotAnimateBlock) != nil) {
// One single non-animated node causes the whole layout update to be non-animated
invalidationStyle = ASCollectionViewInvalidationStyleWithoutAnimation;
break;
}
}
}
_nextLayoutInvalidationStyle = invalidationStyle;
}
#pragma mark - _ASDisplayView behavior substitutions
// Need these to drive interfaceState so we know when we are visible, if not nested in another range-managing element.
// Because our superclass is a true UIKit class, we cannot also subclass _ASDisplayView.
- (void)willMoveToWindow:(UIWindow *)newWindow
{
BOOL visible = (newWindow != nil);
ASDisplayNode *node = self.collectionNode;
if (visible && !node.inHierarchy) {
[node __enterHierarchy];
}
}
- (void)didMoveToWindow
{
BOOL visible = (self.window != nil);
ASDisplayNode *node = self.collectionNode;
if (!visible && node.inHierarchy) {
[node __exitHierarchy];
}
// Updating the visible node index paths only for not range managed nodes. Range managed nodes will get their
// their update in the layout pass
if (![node supportsRangeManagedInterfaceState]) {
[_rangeController setNeedsUpdate];
[_rangeController updateIfNeeded];
}
// When we aren't visible, we will only fetch up to the visible area. Now that we are visible,
// we will fetch visible area + leading screens, so we need to check.
if (visible) {
[self _checkForBatchFetching];
}
}
#pragma mark ASCALayerExtendedDelegate
/**
* TODO: This code was added when we used @c calculatedSize as the size for
* items (e.g. collectionView:layout:sizeForItemAtIndexPath:) and so it
* was critical that we remeasured all nodes at this time.
*
* The assumption was that cv-bounds-size-change -> constrained-size-change, so
* this was the time when we get new constrained sizes for all items and remeasure
* them. However, the constrained sizes for items can be invalidated for many other
* reasons, hence why we never reuse the old constrained size anymore.
*
* UICollectionView inadvertently triggers a -prepareLayout call to its layout object
* between [super setFrame:] and [self layoutSubviews] during size changes. So we need
* to get in there and re-measure our nodes before that -prepareLayout call.
* We can't wait until -layoutSubviews or the end of -setFrame:.
*
* @see @p testThatNodeCalculatedSizesAreUpdatedBeforeFirstPrepareLayoutAfterRotation
*/
- (void)layer:(CALayer *)layer didChangeBoundsWithOldValue:(CGRect)oldBounds newValue:(CGRect)newBounds
{
if (_hasDataControllerLayoutDelegate) {
// Let the layout delegate handle bounds changes if it's available.
return;
}
if (self.collectionViewLayout == nil) {
return;
}
CGSize lastUsedSize = _lastBoundsSizeUsedForMeasuringNodes;
if (CGSizeEqualToSize(lastUsedSize, newBounds.size)) {
return;
}
_lastBoundsSizeUsedForMeasuringNodes = newBounds.size;
// Laying out all nodes is expensive.
// We only need to do this if the bounds changed in the non-scrollable direction.
// If, for example, a vertical flow layout has its height changed due to a status bar
// appearance update, we do not need to relayout all nodes.
// For a more permanent fix to the unsafety mentioned above, see https://github.com/facebook/AsyncDisplayKit/pull/2182
ASScrollDirection scrollDirection = self.scrollableDirections;
BOOL fixedVertically = (ASScrollDirectionContainsVerticalDirection(scrollDirection) == NO);
BOOL fixedHorizontally = (ASScrollDirectionContainsHorizontalDirection(scrollDirection) == NO);
BOOL changedInNonScrollingDirection = (fixedHorizontally && newBounds.size.width != lastUsedSize.width) || (fixedVertically && newBounds.size.height != lastUsedSize.height);
if (changedInNonScrollingDirection) {
[_dataController relayoutAllNodes];
[_dataController waitUntilAllUpdatesAreCommitted];
// We need to ensure the size requery is done before we update our layout.
[self.collectionViewLayout invalidateLayout];
}
}
#pragma mark - UICollectionView dead-end intercepts
- (void)setPrefetchDataSource:(id<UICollectionViewDataSourcePrefetching>)prefetchDataSource
{
return;
}
- (void)setPrefetchingEnabled:(BOOL)prefetchingEnabled
{
return;
}
#if ASDISPLAYNODE_ASSERTIONS_ENABLED // Remove implementations entirely for efficiency if not asserting.
// intercepted due to not being supported by ASCollectionView (prevent bugs caused by usage)
- (BOOL)collectionView:(UICollectionView *)collectionView canMoveItemAtIndexPath:(NSIndexPath *)indexPath NS_AVAILABLE_IOS(9_0)
{
ASDisplayNodeAssert(![self.asyncDataSource respondsToSelector:_cmd], @"%@ is not supported by ASCollectionView - please remove or disable this data source method.", NSStringFromSelector(_cmd));
return NO;
}
- (void)collectionView:(UICollectionView *)collectionView moveItemAtIndexPath:(NSIndexPath *)sourceIndexPath toIndexPath:(NSIndexPath*)destinationIndexPath NS_AVAILABLE_IOS(9_0)
{
ASDisplayNodeAssert(![self.asyncDataSource respondsToSelector:_cmd], @"%@ is not supported by ASCollectionView - please remove or disable this data source method.", NSStringFromSelector(_cmd));
}
#endif
@end