Merge pull request #1766 from hannahmbanana/collectionLayout

[ASCollectionView, ASCellNode] Add support applyLayoutAttributes: on ASCellNode

AsyncDisplayKit/ASCellNode.h

@@ -99,6 +99,13 @@ typedef NS_ENUM(NSUInteger, ASCellNodeVisibilityEvent) {
 - (void)touchesEnded:(NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event ASDISPLAYNODE_REQUIRES_SUPER;
 - (void)touchesCancelled:(nullable NSSet<UITouch *> *)touches withEvent:(nullable UIEvent *)event ASDISPLAYNODE_REQUIRES_SUPER;
 
+/** 
+ * Called by the system when ASCellNode is used with an ASCollectionNode.  It will not be called by ASTableNode.
+ * When the UICollectionViewLayout object returns a new UICollectionViewLayoutAttributes object, the corresponding ASCellNode will be updated.
+ * See UICollectionViewCell's applyLayoutAttributes: for a full description.
+*/
+- (void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes;
+
 /**
  * @abstract Initializes a cell with a given view controller block.
  *

AsyncDisplayKit/ASCellNode.mm

@@ -211,6 +211,11 @@
 
 #pragma clang diagnostic pop
 
+- (void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes
+{
+  // To be overriden by subclasses
+}
+
 - (void)cellNodeVisibilityEvent:(ASCellNodeVisibilityEvent)event inScrollView:(UIScrollView *)scrollView withCellFrame:(CGRect)cellFrame
 {
   // To be overriden by subclasses

AsyncDisplayKit/ASCollectionView.mm

@@ -58,6 +58,11 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
   _node.highlighted = highlighted;
 }
 
+- (void)applyLayoutAttributes:(UICollectionViewLayoutAttributes *)layoutAttributes
+{
+  [_node applyLayoutAttributes:layoutAttributes];
+}
+
 @end
 
 #pragma mark -