[ASPagerNode] New API tweaks. Support setting delegate + dataSource on ASCollectionNode and ASTableNode without triggering view creation.

AsyncDisplayKit/ASCollectionNode.h

@@ -17,6 +17,9 @@
 - (instancetype)initWithCollectionViewLayout:(UICollectionViewLayout *)layout;
 - (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout;
 
+@property (weak, nonatomic) id <ASCollectionDelegate>   delegate;
+@property (weak, nonatomic) id <ASCollectionDataSource> dataSource;
+
 @property (nonatomic, readonly) ASCollectionView *view;
 
 /**

AsyncDisplayKit/ASCollectionNode.m

@@ -9,7 +9,19 @@
 #import "ASCollectionNode.h"
 #import "ASDisplayNode+Subclasses.h"
 
-@interface ASCollectionView (Internal)
+@interface _ASCollectionPendingState : NSObject
+@property (weak, nonatomic) id <ASCollectionDelegate>   delegate;
+@property (weak, nonatomic) id <ASCollectionDataSource> dataSource;
+@end
+
+@implementation _ASCollectionPendingState
+@end
+
+@interface ASCollectionNode ()
+@property (nonatomic) _ASCollectionPendingState *pendingState;
+@end
+
+@interface ASCollectionView ()
 - (instancetype)_initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout;
 @end
 
@@ -29,12 +41,59 @@
 
 - (instancetype)initWithFrame:(CGRect)frame collectionViewLayout:(UICollectionViewLayout *)layout
 {
-  if (self = [super initWithViewBlock:^UIView *{ return [[ASCollectionView alloc] _initWithFrame:frame collectionViewLayout:layout]; }]) {
+  ASDisplayNodeViewBlock collectionViewBlock = ^UIView *{
+    return [[ASCollectionView alloc] _initWithFrame:frame collectionViewLayout:layout];
+  };
+  
+  if (self = [super initWithViewBlock:collectionViewBlock]) {
     return self;
   }
   return nil;
 }
 
+- (void)didLoad
+{
+  [super didLoad];
+  
+  if (_pendingState) {
+    _ASCollectionPendingState *pendingState = _pendingState;
+    self.pendingState = nil;
+    
+    ASCollectionView *view = self.view;
+    view.asyncDelegate     = pendingState.delegate;
+    view.asyncDataSource   = pendingState.dataSource;
+  }
+}
+
+- (_ASCollectionPendingState *)pendingState
+{
+  if (!_pendingState && ![self isNodeLoaded]) {
+    self.pendingState = [[_ASCollectionPendingState alloc] init];
+  }
+  ASDisplayNodeAssert(![self isNodeLoaded] || !_pendingState, @"ASCollectionNode should not have a pendingState once it is loaded");
+  return _pendingState;
+}
+
+- (void)setDelegate:(id <ASCollectionDelegate>)delegate
+{
+  if ([self pendingState]) {
+    _pendingState.delegate = delegate;
+  } else {
+    ASDisplayNodeAssert([self isNodeLoaded], @"ASCollectionNode should be loaded if pendingState doesn't exist");
+    self.view.asyncDelegate = delegate;
+  }
+}
+
+- (void)setDataSource:(id <ASCollectionDataSource>)dataSource
+{
+  if ([self pendingState]) {
+    _pendingState.dataSource = dataSource;
+  } else {
+    ASDisplayNodeAssert([self isNodeLoaded], @"ASCollectionNode should be loaded if pendingState doesn't exist");
+    self.view.asyncDataSource = dataSource;
+  }
+}
+
 - (ASCollectionView *)view
 {
   return (ASCollectionView *)[super view];

AsyncDisplayKit/ASCollectionView.h

@@ -286,6 +286,8 @@
 /**
  * This is a node-based UICollectionViewDataSource.
  */
+@protocol ASCollectionDataSource <ASCollectionViewDataSource>
+@end
 @protocol ASCollectionViewDataSource <ASCommonCollectionViewDataSource, NSObject>
 
 /**
@@ -347,6 +349,8 @@
 /**
  * This is a node-based UICollectionViewDelegate.
  */
+@protocol ASCollectionDelegate <ASCollectionViewDelegate>
+@end
 @protocol ASCollectionViewDelegate <ASCommonCollectionViewDelegate, NSObject>
 
 @optional

AsyncDisplayKit/ASPagerNode.h

@@ -12,7 +12,21 @@
 
 @interface ASPagerNode : ASCollectionNode
 
-@property (weak, nonatomic) id<ASPagerNodeDataSource> dataSource;
+// Configures a default horizontal, paging flow layout with 0 inter-item spacing.
+- (instancetype)init;
+
+// Initializer with custom-configured flow layout properties.
+- (instancetype)initWithFlowLayout:(UICollectionViewFlowLayout *)flowLayout;
+
+// The underlying ASCollectionView object.
+- (ASCollectionView *)collectionView;
+
+// Delegate is optional, and uses the same protocol as ASCollectionNode.
+// This includes UIScrollViewDelegate as well as most methods from UICollectionViewDelegate, like willDisplay...
+@property (weak, nonatomic) id <ASCollectionDelegate>  delegate;
+
+// Data Source is required, and uses a different protocol from ASCollectionNode.
+@property (weak, nonatomic) id <ASPagerNodeDataSource> dataSource;
 
 - (void)scrollToPageAtIndex:(NSInteger)index animated:(BOOL)animated;
 
@@ -20,8 +34,10 @@
 
 @protocol ASPagerNodeDataSource <NSObject>
 
+// This method replaces -collectionView:numberOfItemsInSection:
 - (NSInteger)numberOfPagesInPagerNode:(ASPagerNode *)pagerNode;
 
+// This method replaces -collectionView:nodeForItemAtIndexPath:
 - (ASCellNode *)pagerNode:(ASPagerNode *)pagerNode nodeAtIndex:(NSInteger)index;
 
-@end
+@end

AsyncDisplayKit/ASPagerNode.m

@@ -7,11 +7,14 @@
 //
 
 #import "ASPagerNode.h"
+#import "ASDelegateProxy.h"
 
 #import <AsyncDisplayKit/AsyncDisplayKit.h>
 
 @interface ASPagerNode () <ASCollectionViewDataSource, ASCollectionViewDelegateFlowLayout> {
   UICollectionViewFlowLayout *_flowLayout;
+  ASPagerNodeProxy *_proxy;
+  id <ASPagerNodeDataSource> _pagerDataSource;
 }
 
 @end
@@ -25,6 +28,11 @@
   flowLayout.minimumInteritemSpacing = 0;
   flowLayout.minimumLineSpacing = 0;
   
+  return [self initWithFlowLayout:flowLayout];
+}
+
+- (instancetype)initWithFlowLayout:(UICollectionViewFlowLayout *)flowLayout
+{
   self = [super initWithCollectionViewLayout:flowLayout];
   if (self != nil) {
     _flowLayout = flowLayout;
@@ -32,17 +40,38 @@
   return self;
 }
 
+- (ASCollectionView *)collectionView
+{
+  return self.view;
+}
+
+- (void)setDataSource:(id <ASPagerNodeDataSource>)pagerDataSource
+{
+  if (pagerDataSource != _pagerDataSource) {
+    _pagerDataSource = pagerDataSource;
+    _proxy = pagerDataSource ? [[ASPagerNodeProxy alloc] initWithTarget:pagerDataSource interceptor:self] : nil;
+    super.dataSource = _proxy;
+  }
+}
+
+- (id <ASPagerNodeDataSource>)dataSource
+{
+  return _pagerDataSource;
+}
+
 - (void)didLoad
 {
   [super didLoad];
   
-  self.view.asyncDataSource = self;
+  ASCollectionView *cv = self.view;
-  self.view.asyncDelegate = self;
+  cv.asyncDataSource = self;
+  cv.asyncDelegate = self;
   
-  self.view.pagingEnabled = YES;
+  cv.pagingEnabled = YES;
-  self.view.allowsSelection = NO;
+  cv.allowsSelection = NO;
-  self.view.showsVerticalScrollIndicator = NO;
+  cv.showsVerticalScrollIndicator = NO;
-  self.view.showsHorizontalScrollIndicator = NO;
+  cv.showsHorizontalScrollIndicator = NO;
+  cv.scrollsToTop = NO;
   
   ASRangeTuningParameters preloadParams = { .leadingBufferScreenfuls = 2.0, .trailingBufferScreenfuls = 2.0 };
   ASRangeTuningParameters renderParams = { .leadingBufferScreenfuls = 1.0, .trailingBufferScreenfuls = 1.0 };
@@ -62,14 +91,14 @@
 
 - (ASCellNode *)collectionView:(ASCollectionView *)collectionView nodeForItemAtIndexPath:(NSIndexPath *)indexPath
 {
-  ASDisplayNodeAssert(self.dataSource != nil, @"ASPagerNode must have a data source to load paging nodes");
+  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load paging nodes");
-  return [self.dataSource pagerNode:self nodeAtIndex:indexPath.item];
+  return [_pagerDataSource pagerNode:self nodeAtIndex:indexPath.item];
 }
 
 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 {
-  ASDisplayNodeAssert(self.dataSource != nil, @"ASPagerNode must have a data source to load paging nodes");
+  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load paging nodes");
-  return [self.dataSource numberOfPagesInPagerNode:self];
+  return [_pagerDataSource numberOfPagesInPagerNode:self];
 }
 
 - (ASSizeRange)collectionView:(ASCollectionView *)collectionView constrainedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath

AsyncDisplayKit/ASTableNode.h

@@ -18,4 +18,8 @@
 
 @property (nonatomic, readonly) ASTableView *view;
 
+// These properties can be set without triggering the view to be created, so it's fine to set them in -init.
+@property (weak, nonatomic) id <ASTableDelegate>   delegate;
+@property (weak, nonatomic) id <ASTableDataSource> dataSource;
+
 @end

AsyncDisplayKit/ASTableNode.m

@@ -8,18 +8,71 @@
 
 #import "ASTableNode.h"
 
+@interface _ASTablePendingState : NSObject
+@property (weak, nonatomic) id <ASTableDelegate>   delegate;
+@property (weak, nonatomic) id <ASTableDataSource> dataSource;
+@end
+
+@implementation _ASTablePendingState
+@end
+
+@interface ASTableNode ()
+@property (nonatomic) _ASTablePendingState *pendingState;
+@end
+
 @implementation ASTableNode
 
 - (instancetype)initWithStyle:(UITableViewStyle)style
 {
-  if (self = [super initWithViewBlock:^UIView *{
+  if (self = [super initWithViewBlock:^UIView *{ return [[ASTableView alloc] initWithFrame:CGRectZero style:style]; }]) {
-    return [[ASTableView alloc] initWithFrame:CGRectZero style:style];
-  }]) {
     return self;
   }
   return nil;
 }
 
+- (void)didLoad
+{
+  [super didLoad];
+  
+  if (_pendingState) {
+    _ASTablePendingState *pendingState = _pendingState;
+    self.pendingState = nil;
+    
+    ASTableView *view    = self.view;
+    view.asyncDelegate   = pendingState.delegate;
+    view.asyncDataSource = pendingState.dataSource;
+  }
+}
+
+- (_ASTablePendingState *)pendingState
+{
+  if (!_pendingState && ![self isNodeLoaded]) {
+    self.pendingState = [[_ASTablePendingState alloc] init];
+  }
+  ASDisplayNodeAssert(![self isNodeLoaded] || !_pendingState, @"ASTableNode should not have a pendingState once it is loaded");
+  return _pendingState;
+}
+
+- (void)setDelegate:(id <ASTableDelegate>)delegate
+{
+  if ([self pendingState]) {
+    _pendingState.delegate = delegate;
+  } else {
+    ASDisplayNodeAssert([self isNodeLoaded], @"ASTableNode should be loaded if pendingState doesn't exist");
+    self.view.asyncDelegate = delegate;
+  }
+}
+
+- (void)setDataSource:(id <ASTableDataSource>)dataSource
+{
+  if ([self pendingState]) {
+    _pendingState.dataSource = dataSource;
+  } else {
+    ASDisplayNodeAssert([self isNodeLoaded], @"ASTableNode should be loaded if pendingState doesn't exist");
+    self.view.asyncDataSource = dataSource;
+  }
+}
+
 - (ASTableView *)view
 {
   return (ASTableView *)[super view];

AsyncDisplayKit/ASTableView.h

@@ -280,6 +280,8 @@
 /**
  * This is a node-based UITableViewDataSource.
  */
+@protocol ASTableDataSource <ASTableViewDataSource>
+@end
 @protocol ASTableViewDataSource <ASCommonTableViewDataSource, NSObject>
 
 /**
@@ -324,6 +326,8 @@
  * Note that -tableView:heightForRowAtIndexPath: has been removed; instead, your custom ASCellNode subclasses are
  * responsible for deciding their preferred onscreen height in -calculateSizeThatFits:.
  */
+@protocol ASTableDelegate <ASTableViewDelegate>
+@end
 @protocol ASTableViewDelegate <ASCommonTableViewDelegate, NSObject>
 
 @optional

AsyncDisplayKit/Details/ASDelegateProxy.h

@@ -49,3 +49,7 @@
 
 @interface ASCollectionViewProxy : ASDelegateProxy
 @end
+
+@interface ASPagerNodeProxy : ASDelegateProxy
+@end
+

AsyncDisplayKit/Details/ASDelegateProxy.m

@@ -60,6 +60,20 @@
 
 @end
 
+@implementation ASPagerNodeProxy
+
+- (BOOL)interceptsSelector:(SEL)selector
+{
+  return (
+          // handled by ASPagerNodeDataSource node<->cell machinery
+          selector == @selector(collectionView:nodeForItemAtIndexPath:) ||
+          selector == @selector(collectionView:numberOfItemsInSection:) ||
+          selector == @selector(collectionView:constrainedSizeForNodeAtIndexPath:)
+          );
+}
+
+@end
+
 @implementation ASDelegateProxy {
   id <NSObject> __weak _target;
   id <ASDelegateProxyInterceptor> __weak _interceptor;

AsyncDisplayKit/Layout/ASStaticLayoutSpec.mm

@@ -39,33 +39,34 @@
 
 - (ASLayout *)measureWithSizeRange:(ASSizeRange)constrainedSize
 {
-  CGSize size = {
+  CGSize maxConstrainedSize = CGSizeMake(constrainedSize.max.width, constrainedSize.max.height);
-    constrainedSize.max.width,
+  
-    constrainedSize.max.height
+  NSArray *children = self.children;
-  };
+  NSMutableArray *sublayouts = [NSMutableArray arrayWithCapacity:children.count];
 
-  NSMutableArray *sublayouts = [NSMutableArray arrayWithCapacity:self.children.count];
+  for (id<ASLayoutable> child in children) {
-  for (id<ASLayoutable> child in self.children) {
+    CGPoint layoutPosition = child.layoutPosition;
-    CGSize autoMaxSize = {
+    CGSize autoMaxSize = CGSizeMake(maxConstrainedSize.width  - layoutPosition.x,
-      constrainedSize.max.width - child.layoutPosition.x,
+                                    maxConstrainedSize.height - layoutPosition.y);
-      constrainedSize.max.height - child.layoutPosition.y
+    
-    };
+    ASRelativeSizeRange childSizeRange = child.sizeRange;
-    ASSizeRange childConstraint = ASRelativeSizeRangeEqualToRelativeSizeRange(ASRelativeSizeRangeUnconstrained, child.sizeRange)
+    BOOL childIsUnconstrained = ASRelativeSizeRangeEqualToRelativeSizeRange(ASRelativeSizeRangeUnconstrained, childSizeRange);
-      ? ASSizeRangeMake({0, 0}, autoMaxSize)
+    ASSizeRange childConstraint = childIsUnconstrained ? ASSizeRangeMake({0, 0}, autoMaxSize)
-      : ASRelativeSizeRangeResolve(child.sizeRange, size);
+                                                       : ASRelativeSizeRangeResolve(childSizeRange, maxConstrainedSize);
+    
     ASLayout *sublayout = [child measureWithSizeRange:childConstraint];
-    sublayout.position = child.layoutPosition;
+    sublayout.position = layoutPosition;
     [sublayouts addObject:sublayout];
   }
   
-  size.width = constrainedSize.min.width;
+  CGSize size = CGSizeMake(constrainedSize.min.width, constrainedSize.min.height);
-  for (ASLayout *sublayout in sublayouts) {
-    size.width = MAX(size.width, sublayout.position.x + sublayout.size.width);
-  }
 
-  size.height = constrainedSize.min.height;
   for (ASLayout *sublayout in sublayouts) {
-    size.height = MAX(size.height, sublayout.position.y + sublayout.size.height);
+    CGPoint sublayoutPosition = sublayout.position;
+    CGSize  sublayoutSize     = sublayout.size;
+    
+    size.width  = MAX(size.width,  sublayoutPosition.x + sublayoutSize.width);
+    size.height = MAX(size.height, sublayoutPosition.y + sublayoutSize.height);
   }
 
   return [ASLayout layoutWithLayoutableObject:self
@@ -75,12 +76,12 @@
 
 - (void)setChild:(id<ASLayoutable>)child forIdentifier:(NSString *)identifier
 {
-  ASDisplayNodeAssert(NO, @"ASStackLayoutSpec only supports setChildren");
+  ASDisplayNodeAssert(NO, @"ASStaticLayoutSpec only supports setChildren");
 }
 
 - (id<ASLayoutable>)childForIdentifier:(NSString *)identifier
 {
-  ASDisplayNodeAssert(NO, @"ASStackLayoutSpec only supports children");
+  ASDisplayNodeAssert(NO, @"ASStaticLayoutSpec only supports children");
   return nil;
 }