Fix Pager Node Issues (#3028)

* Fix pager node and deprecate zeroContentInsets flag

* Do it with the visible state callback

* There we are

* Put viewController in node debug description

AsyncDisplayKit.xcodeproj/project.pbxproj

@@ -327,6 +327,10 @@
 		CC4C2A791D88E3BF0039ACAB /* ASTraceEvent.m in Sources */ = {isa = PBXBuildFile; fileRef = CC4C2A761D88E3BF0039ACAB /* ASTraceEvent.m */; };
 		CC54A81C1D70079800296A24 /* ASDispatch.h in Headers */ = {isa = PBXBuildFile; fileRef = CC54A81B1D70077A00296A24 /* ASDispatch.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		CC54A81E1D7008B300296A24 /* ASDispatchTests.m in Sources */ = {isa = PBXBuildFile; fileRef = CC54A81D1D7008B300296A24 /* ASDispatchTests.m */; };
+		CC55A70D1E529FA200594372 /* UIResponder+AsyncDisplayKit.h in Headers */ = {isa = PBXBuildFile; fileRef = CC55A70B1E529FA200594372 /* UIResponder+AsyncDisplayKit.h */; settings = {ATTRIBUTES = (Public, ); }; };
+		CC55A70E1E529FA200594372 /* UIResponder+AsyncDisplayKit.m in Sources */ = {isa = PBXBuildFile; fileRef = CC55A70C1E529FA200594372 /* UIResponder+AsyncDisplayKit.m */; };
+		CC55A7111E52A0F200594372 /* ASResponderChainEnumerator.h in Headers */ = {isa = PBXBuildFile; fileRef = CC55A70F1E52A0F200594372 /* ASResponderChainEnumerator.h */; };
+		CC55A7121E52A0F200594372 /* ASResponderChainEnumerator.m in Sources */ = {isa = PBXBuildFile; fileRef = CC55A7101E52A0F200594372 /* ASResponderChainEnumerator.m */; };
 		CC57EAF71E3939350034C595 /* ASCollectionView+Undeprecated.h in Headers */ = {isa = PBXBuildFile; fileRef = CC2E317F1DAC353700EEE891 /* ASCollectionView+Undeprecated.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		CC57EAF81E3939450034C595 /* ASTableView+Undeprecated.h in Headers */ = {isa = PBXBuildFile; fileRef = CC512B841DAC45C60054848E /* ASTableView+Undeprecated.h */; settings = {ATTRIBUTES = (Private, ); }; };
 		CC58AA4B1E398E1D002C8CB4 /* ASBlockTypes.h in Headers */ = {isa = PBXBuildFile; fileRef = CC58AA4A1E398E1D002C8CB4 /* ASBlockTypes.h */; settings = {ATTRIBUTES = (Public, ); }; };
@@ -711,6 +715,10 @@
 		CC512B841DAC45C60054848E /* ASTableView+Undeprecated.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "ASTableView+Undeprecated.h"; sourceTree = "<group>"; };
 		CC54A81B1D70077A00296A24 /* ASDispatch.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = ASDispatch.h; sourceTree = "<group>"; };
 		CC54A81D1D7008B300296A24 /* ASDispatchTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; lineEnding = 0; path = ASDispatchTests.m; sourceTree = "<group>"; xcLanguageSpecificationIdentifier = xcode.lang.objc; };
+		CC55A70B1E529FA200594372 /* UIResponder+AsyncDisplayKit.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = "UIResponder+AsyncDisplayKit.h"; sourceTree = "<group>"; };
+		CC55A70C1E529FA200594372 /* UIResponder+AsyncDisplayKit.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = "UIResponder+AsyncDisplayKit.m"; sourceTree = "<group>"; };
+		CC55A70F1E52A0F200594372 /* ASResponderChainEnumerator.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASResponderChainEnumerator.h; sourceTree = "<group>"; };
+		CC55A7101E52A0F200594372 /* ASResponderChainEnumerator.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = ASResponderChainEnumerator.m; sourceTree = "<group>"; };
 		CC57EAF91E394EA40034C595 /* Info.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; path = Info.plist; sourceTree = "<group>"; };
 		CC58AA4A1E398E1D002C8CB4 /* ASBlockTypes.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASBlockTypes.h; sourceTree = "<group>"; };
 		CC7FD9DC1BB5E962005CCB2B /* ASPhotosFrameworkImageRequest.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; path = ASPhotosFrameworkImageRequest.h; sourceTree = "<group>"; };
@@ -927,6 +935,8 @@
 				DB55C2651C641AE4004EDCF5 /* ASContextTransitioning.h */,
 				68FC85E71CE29C7D00EDD713 /* ASVisibilityProtocols.h */,
 				68FC85E81CE29C7D00EDD713 /* ASVisibilityProtocols.m */,
+				CC55A70B1E529FA200594372 /* UIResponder+AsyncDisplayKit.h */,
+				CC55A70C1E529FA200594372 /* UIResponder+AsyncDisplayKit.m */,
 				690ED5911E36D118000627C0 /* tvOS */,
 				DE89C1691DCEB9CC00D49D74 /* Debug */,
 				058D09E1195D050800B7D73C /* Details */,
@@ -1120,6 +1130,8 @@
 		058D0A01195D050800B7D73C /* Private */ = {
 			isa = PBXGroup;
 			children = (
+				CC55A70F1E52A0F200594372 /* ASResponderChainEnumerator.h */,
+				CC55A7101E52A0F200594372 /* ASResponderChainEnumerator.m */,
 				6947B0BB1E36B4E30007C478 /* Layout */,
 				CCE04B2A1E313EDA006AEBBB /* Collection Data Adapter */,
 				058D0A03195D050800B7D73C /* _ASCoreAnimationExtras.h */,
@@ -1398,6 +1410,7 @@
 				B35062151B010EFD0018CF92 /* ASBatchContext.h in Headers */,
 				B35061F31B010EFD0018CF92 /* ASCellNode.h in Headers */,
 				34EFC7631B701CBF00AD841F /* ASCenterLayoutSpec.h in Headers */,
+				CC55A7111E52A0F200594372 /* ASResponderChainEnumerator.h in Headers */,
 				18C2ED7F1B9B7DE800F627B3 /* ASCollectionNode.h in Headers */,
 				B35061F51B010EFD0018CF92 /* ASCollectionView.h in Headers */,
 				ACE87A2C1D73696800D7FF06 /* ASSectionContext.h in Headers */,
@@ -1441,6 +1454,7 @@
 				254C6B771BF94DF4003EC431 /* ASTextKitAttributes.h in Headers */,
 				254C6B7D1BF94DF4003EC431 /* ASTextKitShadower.h in Headers */,
 				690ED58E1E36BCA6000627C0 /* ASLayoutElementStylePrivate.h in Headers */,
+				CC55A70D1E529FA200594372 /* UIResponder+AsyncDisplayKit.h in Headers */,
 				254C6B731BF94DF4003EC431 /* ASTextKitCoreTextAdditions.h in Headers */,
 				254C6B7A1BF94DF4003EC431 /* ASTextKitRenderer.h in Headers */,
 				69CB62AC1CB8165900024920 /* _ASDisplayViewAccessiblity.h in Headers */,
@@ -1827,6 +1841,7 @@
 				18C2ED831B9B7DE800F627B3 /* ASCollectionNode.mm in Sources */,
 				E55D86331CA8A14000A0C26F /* ASLayoutElement.mm in Sources */,
 				68FC85EC1CE29C7D00EDD713 /* ASVisibilityProtocols.m in Sources */,
+				CC55A7121E52A0F200594372 /* ASResponderChainEnumerator.m in Sources */,
 				68B8A4E41CBDB958007E4543 /* ASWeakProxy.m in Sources */,
 				9C70F20A1CDBE949007D6C76 /* ASTableNode.mm in Sources */,
 				69CB62AE1CB8165900024920 /* _ASDisplayViewAccessiblity.mm in Sources */,
@@ -1905,6 +1920,7 @@
 				254C6B871BF94F8A003EC431 /* ASTextKitEntityAttribute.m in Sources */,
 				34566CB31BC1213700715E6B /* ASPhotosFrameworkImageRequest.m in Sources */,
 				254C6B831BF94F8A003EC431 /* ASTextKitCoreTextAdditions.m in Sources */,
+				CC55A70E1E529FA200594372 /* UIResponder+AsyncDisplayKit.m in Sources */,
 				697796611D8AC8D3007E93D7 /* ASLayoutSpec+Subclasses.mm in Sources */,
 				B350623B1B010EFD0018CF92 /* NSMutableAttributedString+TextKitAdditions.m in Sources */,
 				044284FD1BAA365100D16268 /* UICollectionViewLayout+ASConvenience.m in Sources */,

AsyncDisplayKit/ASCollectionView.h

@@ -111,6 +111,10 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, assign) BOOL inverted;
 
+@end
+
+@interface ASCollectionView (Deprecated)
+
 /**
  * Forces the .contentInset to be UIEdgeInsetsZero.
  *
@@ -119,11 +123,7 @@ NS_ASSUME_NONNULL_BEGIN
  * automaticallyAdjustsScrollViewInsets, which may not be accessible.  ASPagerNode uses this to ensure
  * its flow layout behaves predictably and does not log undefined layout warnings.
  */
-@property (nonatomic) BOOL zeroContentInsets;
-
-@end
-
-@interface ASCollectionView (Deprecated)
+@property (nonatomic) BOOL zeroContentInsets ASDISPLAYNODE_DEPRECATED_MSG("Set automaticallyAdjustsScrollViewInsets=NO on your view controller instead.");
 
 /**
  * The object that acts as the asynchronous delegate of the collection view

AsyncDisplayKit/ASCollectionView.mm

@@ -26,6 +26,7 @@
 #import <AsyncDisplayKit/_ASCollectionViewCell.h>
 #import <AsyncDisplayKit/_ASDisplayLayer.h>
 #import <AsyncDisplayKit/ASCollectionViewLayoutFacilitatorProtocol.h>
+#import <AsyncDisplayKit/ASPagerNode.h>
 #import <AsyncDisplayKit/ASSectionContext.h>
 #import <AsyncDisplayKit/ASCollectionView+Undeprecated.h>
 #import <AsyncDisplayKit/_ASHierarchyChangeSet.h>
@@ -94,6 +95,8 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
   
   CGPoint _deceleratingVelocity;
 
+  BOOL _zeroContentInsets;
+  
   ASCollectionViewInvalidationStyle _nextLayoutInvalidationStyle;
   
   /**
@@ -584,6 +587,16 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
   return [_rangeController tuningParametersForRangeMode:rangeMode rangeType:rangeType];
 }
 
+- (void)setZeroContentInsets:(BOOL)zeroContentInsets
+{
+  _zeroContentInsets = zeroContentInsets;
+}
+
+- (BOOL)zeroContentInsets
+{
+  return _zeroContentInsets;
+}
+
 - (CGSize)calculatedSizeForNodeAtIndexPath:(NSIndexPath *)indexPath
 {
   return [[self nodeForItemAtIndexPath:indexPath] calculatedSize];
@@ -1911,19 +1924,11 @@ static NSString * const kReuseIdentifier = @"_ASCollectionReuseIdentifier";
     BOOL changedInNonScrollingDirection = (fixedHorizontally && newBounds.size.width != lastUsedSize.width) || (fixedVertically && newBounds.size.height != lastUsedSize.height);
 
     if (changedInNonScrollingDirection) {
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wdeprecated-declarations"
-      // This actually doesn't perform an animation, but prevents the transaction block from being processed in the
-      // data controller's prevent animation block that would interrupt an interrupted relayout happening in an animation block
-      // ie. ASCollectionView bounds change on rotation or multi-tasking split view resize.
-      [self performBatchAnimated:YES updates:^{
       [_dataController relayoutAllNodes];
-      } completion:nil];
+      [_dataController waitUntilAllUpdatesAreCommitted];
       // We need to ensure the size requery is done before we update our layout.
-      [self waitUntilAllUpdatesAreCommitted];
       [self.collectionViewLayout invalidateLayout];
     }
-#pragma clang diagnostic pop
   }
 }
 

AsyncDisplayKit/ASDisplayNode.mm

@@ -36,6 +36,7 @@
 #import <AsyncDisplayKit/ASRunLoopQueue.h>
 #import <AsyncDisplayKit/ASTraitCollection.h>
 #import <AsyncDisplayKit/ASWeakProxy.h>
+#import <AsyncDisplayKit/ASResponderChainEnumerator.h>
 
 /**
  * Assert if the current thread owns a mutex.
@@ -3784,6 +3785,20 @@ ASDISPLAYNODE_INLINE BOOL nodeIsInRasterizedTree(ASDisplayNode *node) {
     [result addObject:@{ @"frameInWindow" : [NSValue valueWithCGRect:windowFrame] }];
   }
   
+  // Attempt to find view controller.
+  // Note that the convenience method asdk_associatedViewController has an assertion
+  // that it's run on main. Since this is a debug method, let's bypass the assertion
+  // and run up the chain ourselves.
+  if (_view != nil) {
+    for (UIResponder *responder in [_view asdk_responderChainEnumerator]) {
+      UIViewController *vc = ASDynamicCast(responder, UIViewController);
+      if (vc) {
+        [result addObject:@{ @"viewController" : ASObjectDescriptionMakeTiny(vc) }];
+        break;
+      }
+    }
+  }
+  
   if (_view != nil) {
     [result addObject:@{ @"frame" : [NSValue valueWithCGRect:_view.frame] }];
   } else if (_layer != nil) {

AsyncDisplayKit/ASPagerFlowLayout.m

@@ -11,58 +11,39 @@
 //
 
 #import <AsyncDisplayKit/ASPagerFlowLayout.h>
+#import <AsyncDisplayKit/ASCellNode.h>
+#import <AsyncDisplayKit/ASCollectionView.h>
 
 @interface ASPagerFlowLayout () {
-  BOOL _didRotate;
-  CGRect _cachedCollectionViewBounds;
-  NSIndexPath *_currentIndexPath;
+  __weak ASCellNode *_currentCellNode;
 }
 
 @end
 
 @implementation ASPagerFlowLayout
 
-- (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset withScrollingVelocity:(CGPoint)velocity
+- (ASCollectionView *)asCollectionView
 {
-  NSInteger currentPage = ceil(proposedContentOffset.x / self.collectionView.bounds.size.width);
-  _currentIndexPath = [NSIndexPath indexPathForItem:currentPage inSection:0];
-  
-  return [super targetContentOffsetForProposedContentOffset:proposedContentOffset withScrollingVelocity:velocity];
+  // Dynamic cast is too slow and not worth it.
+  return (ASCollectionView *)self.collectionView;
 }
 
-
-- (void)prepareForAnimatedBoundsChange:(CGRect)oldBounds
+- (void)prepareLayout
 {
-  // Cache the current page if a rotation did happen. This happens before the rotation animation
-  // is occuring and the bounds changed so we use this as an opportunity to cache the current index path
-  if (_cachedCollectionViewBounds.size.width != self.collectionView.bounds.size.width) {
-      _cachedCollectionViewBounds = self.collectionView.bounds;
-        
-    // Figurring out current page based on the old bounds visible space
-    CGRect visibleRect = oldBounds;
-           
-    CGFloat visibleXCenter = CGRectGetMidX(visibleRect);
-    NSArray<UICollectionViewLayoutAttributes *> *layoutAttributes = [self layoutAttributesForElementsInRect:visibleRect];
-    for (UICollectionViewLayoutAttributes *attributes in layoutAttributes) {
-      if ([attributes representedElementCategory] == UICollectionElementCategoryCell && attributes.center.x == visibleXCenter) {
-        _currentIndexPath = attributes.indexPath;
-        break;
+  [super prepareLayout];
+  if (_currentCellNode == nil) {
+    [self _updateCurrentNode];
   }
-    }
-      
-      _didRotate = YES;
-    }
-    
-    [super prepareForAnimatedBoundsChange:oldBounds];
 }
+
 - (CGPoint)targetContentOffsetForProposedContentOffset:(CGPoint)proposedContentOffset
 {
   // Don't mess around if the user is interacting with the page node. Although if just a rotation happened we should
   // try to use the current index path to not end up setting the target content offset to something in between pages
-    if (_didRotate || (!self.collectionView.isDecelerating && !self.collectionView.isTracking)) {
-        _didRotate = NO;
-        if (_currentIndexPath) {
-          return [self _targetContentOffsetForItemAtIndexPath:_currentIndexPath proposedContentOffset:proposedContentOffset];
+  if (!self.collectionView.decelerating && !self.collectionView.tracking) {
+    NSIndexPath *indexPath = [self.asCollectionView indexPathForNode:_currentCellNode];
+    if (indexPath) {
+      return [self _targetContentOffsetForItemAtIndexPath:indexPath proposedContentOffset:proposedContentOffset];
     }
   }
 
@@ -75,7 +56,7 @@
     return proposedContentOffset;
   }
   
-  UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:_currentIndexPath];
+  UICollectionViewLayoutAttributes *attributes = [self layoutAttributesForItemAtIndexPath:indexPath];
   if (attributes == nil) {
     return proposedContentOffset;
   }
@@ -90,4 +71,34 @@
           [self.collectionView numberOfItemsInSection:0] == 0);
 }
 
+- (void)_updateCurrentNode
+{
+  // Never change node during an animated bounds change (rotation)
+  // NOTE! Listening for -prepareForAnimatedBoundsChange and -finalizeAnimatedBoundsChange
+  // isn't sufficient here! It's broken!
+  NSArray *animKeys = self.collectionView.layer.animationKeys;
+  for (NSString *key in animKeys) {
+    if ([key hasPrefix:@"bounds"]) {
+      return;
+    }
+  }
+  
+  CGRect bounds = self.collectionView.bounds;
+  CGRect rect = CGRectMake(CGRectGetMidX(bounds), CGRectGetMidY(bounds), 1, 1);
+
+  NSIndexPath *indexPath = [self layoutAttributesForElementsInRect:rect].firstObject.indexPath;
+  if (indexPath) {
+    ASCellNode *node = [self.asCollectionView nodeForItemAtIndexPath:indexPath];
+    if (node) {
+      _currentCellNode = node;
+    }
+  }
+}
+
+- (BOOL)shouldInvalidateLayoutForBoundsChange:(CGRect)newBounds
+{
+  [self _updateCurrentNode];
+  return [super shouldInvalidateLayoutForBoundsChange:newBounds];
+}
+
 @end

AsyncDisplayKit/ASPagerNode.h

@@ -120,6 +120,24 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (NSInteger)indexOfPageWithNode:(ASCellNode *)node;
 
+/**
+ * Tells the pager node to allow its view controller to automatically adjust its content insets.
+ *
+ * @see UIViewController.automaticallyAdjustsScrollViewInsets
+ *
+ * @discussion ASPagerNode should usually not have its content insets automatically adjusted
+ * because it scrolls horizontally, and flow layout will log errors because the pages
+ * do not fit between the top & bottom insets of the collection view.
+ *
+ * The default value is NO, which means that ASPagerNode expects that its view controller will
+ * have automaticallyAdjustsScrollViewInsets=NO.
+ *
+ * If this property is NO, but your view controller has automaticallyAdjustsScrollViewInsets=YES,
+ * the pager node will set the property to NO and log a warning message. In the future,
+ * the pager node will just log the warning, and you'll need to configure your view controller on your own.
+ */
+@property (nonatomic, assign) BOOL allowsAutomaticInsetsAdjustment;
+
 @end
 
 NS_ASSUME_NONNULL_END

AsyncDisplayKit/ASPagerNode.m

@@ -12,11 +12,13 @@
 
 #import <AsyncDisplayKit/ASPagerNode.h>
 #import <AsyncDisplayKit/ASDelegateProxy.h>
+#import <AsyncDisplayKit/ASDisplayNode+FrameworkPrivate.h>
 #import <AsyncDisplayKit/ASDisplayNode+Subclasses.h>
 #import <AsyncDisplayKit/ASPagerFlowLayout.h>
 #import <AsyncDisplayKit/ASAssert.h>
 #import <AsyncDisplayKit/ASCellNode.h>
 #import <AsyncDisplayKit/ASCollectionView+Undeprecated.h>
+#import <AsyncDisplayKit/UIResponder+AsyncDisplayKit.h>
 
 @interface ASPagerNode () <ASCollectionDataSource, ASCollectionDelegate, ASCollectionDelegateFlowLayout, ASDelegateProxyInterceptor>
 {
@@ -81,11 +83,6 @@
   cv.showsVerticalScrollIndicator = NO;
   cv.showsHorizontalScrollIndicator = NO;
 
-  // Zeroing contentInset is important, as UIKit will set the top inset for the navigation bar even though
-  // our view is only horizontally scrollable.  This causes UICollectionViewFlowLayout to log a warning.
-  // From here we cannot disable this directly (UIViewController's automaticallyAdjustsScrollViewInsets).
-  cv.zeroContentInsets = YES;
-
   ASRangeTuningParameters minimumRenderParams = { .leadingBufferScreenfuls = 0.0, .trailingBufferScreenfuls = 0.0 };
   ASRangeTuningParameters minimumPreloadParams = { .leadingBufferScreenfuls = 1.0, .trailingBufferScreenfuls = 1.0 };
   [self setTuningParameters:minimumRenderParams forRangeMode:ASLayoutRangeModeMinimum rangeType:ASLayoutRangeTypeDisplay];
@@ -211,4 +208,21 @@
   [self setDelegate:nil];
 }
 
+- (void)didEnterVisibleState
+{
+	[super didEnterVisibleState];
+
+	// Check that our view controller does not automatically set our content insets
+	// It would be better to have a -didEnterHierarchy hook to put this in, but
+	// such a hook doesn't currently exist, and in every use case I can imagine,
+	// the pager is not hosted inside a range-managed node.
+	if (_allowsAutomaticInsetsAdjustment == NO) {
+		UIViewController *vc = [self.view asdk_associatedViewController];
+		if (vc.automaticallyAdjustsScrollViewInsets) {
+			NSLog(@"AsyncDisplayKit: ASPagerNode is setting automaticallyAdjustsScrollViewInsets=NO on its owning view controller %@. This automatic behavior will be disabled in the future. Set allowsAutomaticInsetsAdjustment=YES on the pager node to suppress this behavior.", vc);
+			vc.automaticallyAdjustsScrollViewInsets = NO;
+		}
+	}
+}
+
 @end

AsyncDisplayKit/AsyncDisplayKit.h

@@ -106,6 +106,7 @@
 #import <AsyncDisplayKit/UIImage+ASConvenience.h>
 #import <AsyncDisplayKit/NSArray+Diffing.h>
 #import <AsyncDisplayKit/ASObjectDescriptionHelpers.h>
+#import <AsyncDisplayKit/UIResponder+AsyncDisplayKit.h>
 
 #import <AsyncDisplayKit/AsyncDisplayKit+Debug.h>
 #import <AsyncDisplayKit/ASDisplayNode+Deprecated.h>

AsyncDisplayKit/Private/ASResponderChainEnumerator.h

@@ -0,0 +1,28 @@
+//
+//  ASResponderChainEnumerator.h
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 2/13/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import <UIKit/UIResponder.h>
+#import <AsyncDisplayKit/ASBaseDefines.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+AS_SUBCLASSING_RESTRICTED
+@interface ASResponderChainEnumerator : NSEnumerator
+
+- (instancetype)initWithResponder:(UIResponder *)responder;
+
+@end
+
+@interface UIResponder (ASResponderChainEnumerator)
+
+- (ASResponderChainEnumerator *)asdk_responderChainEnumerator;
+
+@end
+
+
+NS_ASSUME_NONNULL_END

AsyncDisplayKit/Private/ASResponderChainEnumerator.m

@@ -0,0 +1,41 @@
+//
+//  ASResponderChainEnumerator.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 2/13/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import "ASResponderChainEnumerator.h"
+
+@implementation ASResponderChainEnumerator {
+  UIResponder *_currentResponder;
+}
+
+- (instancetype)initWithResponder:(UIResponder *)responder
+{
+  if (self = [super init]) {
+    _currentResponder = responder;
+  }
+  return self;
+}
+
+#pragma mark - NSEnumerator
+
+- (id)nextObject
+{
+  id result = [_currentResponder nextResponder];
+  _currentResponder = result;
+  return result;
+}
+
+@end
+
+@implementation UIResponder (ASResponderChainEnumerator)
+
+- (NSEnumerator *)asdk_responderChainEnumerator
+{
+  return [[ASResponderChainEnumerator alloc] initWithResponder:self];
+}
+
+@end

AsyncDisplayKit/UIResponder+AsyncDisplayKit.h

@@ -0,0 +1,24 @@
+//
+//  UIResponder+AsyncDisplayKit.h
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 2/13/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import <UIKit/UIKit.h>
+
+NS_ASSUME_NONNULL_BEGIN
+
+@interface UIResponder (AsyncDisplayKit)
+
+/**
+ * The nearest view controller above this responder, if one exists.
+ *
+ * This property must be accessed on the main thread.
+ */
+@property (nonatomic, nullable, readonly) __kindof UIViewController *asdk_associatedViewController;
+
+@end
+
+NS_ASSUME_NONNULL_END

AsyncDisplayKit/UIResponder+AsyncDisplayKit.m

@@ -0,0 +1,31 @@
+//
+//  UIResponder+AsyncDisplayKit.m
+//  AsyncDisplayKit
+//
+//  Created by Adlai Holler on 2/13/17.
+//  Copyright © 2017 Facebook. All rights reserved.
+//
+
+#import "UIResponder+AsyncDisplayKit.h"
+
+#import <AsyncDisplayKit/ASAssert.h>
+#import <AsyncDisplayKit/ASBaseDefines.h>
+#import <AsyncDisplayKit/ASResponderChainEnumerator.h>
+
+@implementation UIResponder (AsyncDisplayKit)
+
+- (__kindof UIViewController *)asdk_associatedViewController
+{
+  ASDisplayNodeAssertMainThread();
+  
+  for (UIResponder *responder in [self asdk_responderChainEnumerator]) {
+    UIViewController *vc = ASDynamicCast(responder, UIViewController);
+    if (vc) {
+      return vc;
+    }
+  }
+  return nil;
+}
+
+@end
+

examples/PagerNode/Sample/PageNode.m

@@ -21,9 +21,9 @@
 
 @implementation PageNode
 
-- (ASLayout *)calculateLayoutThatFits:(ASSizeRange)constrainedSize
+- (CGSize)calculateSizeThatFits:(CGSize)constrainedSize
 {
-  return [ASLayout layoutWithLayoutElement:self size:constrainedSize.max];
+  return constrainedSize;
 }
 
 - (void)fetchData

examples/PagerNode/Sample/ViewController.m

@@ -46,7 +46,7 @@ static UIColor *randomColor() {
   
   self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Next" style:UIBarButtonItemStylePlain target:self action:@selector(scrollToNextPage:)];
   self.navigationItem.leftBarButtonItem = [[UIBarButtonItem alloc] initWithTitle:@"Previous" style:UIBarButtonItemStylePlain target:self action:@selector(scrollToPreviousPage:)];
-
+  self.automaticallyAdjustsScrollViewInsets = NO;
   return self;
 }