Add relayout item/row APIs to ASTableView and ASCollectionView.

AsyncDisplayKit/ASCollectionView.h

@@ -191,6 +191,16 @@
  */
 - (void)reloadItemsAtIndexPaths:(NSArray *)indexPaths;
 
+/**
+ * Relayouts the specified item.
+ *
+ * @param indexPath The index path identifying the item to relayout.
+ *
+ * @discussion This method must be called from the main thread. The relayout is excuted on main thread.
+ * The node of the specified item must be updated to cause layout changes before this method is called.
+ */
+- (void)relayoutItemAtIndexPath:(NSIndexPath *)indexPath;
+
 /**
  * Moves the item at a specified location to a destination location.
  *

AsyncDisplayKit/ASCollectionView.mm

@@ -406,6 +406,14 @@ static BOOL _isInterceptedSelector(SEL sel)
   [_dataController reloadRowsAtIndexPaths:indexPaths withAnimationOptions:kASCollectionViewAnimationNone];
 }
 
+- (void)relayoutItemAtIndexPath:(NSIndexPath *)indexPath
+{
+  ASDisplayNodeAssertMainThread();
+  ASCellNode *node = [self nodeForItemAtIndexPath:indexPath];
+  [node setNeedsLayout];
+  [super reloadItemsAtIndexPaths:@[indexPath]];
+}
+
 - (void)moveItemAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath
 {
   ASDisplayNodeAssertMainThread();

AsyncDisplayKit/ASDisplayNode.h

@@ -556,9 +556,13 @@ typedef void (^ASDisplayNodeDidLoadBlock)(ASDisplayNode *node);
  * If this node was measured, calling this method triggers an internal relayout: the calculated layout is invalidated,
  * and the supernode is notified or (if this node is the root one) a full measurement pass is executed using the old constrained size.
  * 
- * Note: If the relayout causes a change in size of the root node that is attached to a container view
- * (table or collection view, for example), the container view must be notified to relayout.
- * For ASTableView and ASCollectionView, an empty batch editing transaction must be triggered to animate to new row / item sizes.
+ * Note: If the relayout causes a change in size of the root node that is attached to a container view, 
+ * the container view must be notified to relayout. 
+ * For ASTableView and ASCollectionView, instead of calling this method directly, 
+ * it is recommended to call -relayoutRowAtIndexPath:withRowAnimation and -relayoutItemAtIndexPath: respectively.
+ *
+ * @see [ASTableView relayoutRowAtIndexPath:withRowAnimation:]
+ * @see [ASCollectionView relayoutItemAtIndexPath:]
  */
 - (void)setNeedsLayout;
 

AsyncDisplayKit/ASTableView.h

@@ -206,6 +206,18 @@
  */
 - (void)reloadRowsAtIndexPaths:(NSArray *)indexPaths withRowAnimation:(UITableViewRowAnimation)animation;
 
+/**
+ * Relayouts the specified row using a given animation effect.
+ *
+ * @param indexPath The index path identifying the row to relayout.
+ *
+ * @param animation A constant that indicates how the relayout is to be animated. See UITableViewRowAnimation.
+ *
+ * @discussion This method must be called from the main thread. The relayout is excuted on main thread. 
+ * The node of the specified row must be updated to cause layout changes before this method is called.
+ */
+- (void)relayoutRowAtIndexPath:(NSIndexPath *)indexPath withRowAnimation:(UITableViewRowAnimation)animation;
+
 /**
  * Moves the row at a specified location to a destination location.
  *

AsyncDisplayKit/ASTableView.mm

@@ -455,6 +455,14 @@ void ASPerformBlockWithoutAnimation(BOOL withoutAnimation, void (^block)()) {
   [_dataController reloadRowsAtIndexPaths:indexPaths withAnimationOptions:animation];
 }
 
+- (void)relayoutRowAtIndexPath:(NSIndexPath *)indexPath withRowAnimation:(UITableViewRowAnimation)animation
+{
+  ASDisplayNodeAssertMainThread();
+  ASCellNode *node = [self nodeForRowAtIndexPath:indexPath];
+  [node setNeedsLayout];
+  [super reloadRowsAtIndexPaths:@[indexPath] withRowAnimation:animation];
+}
+
 - (void)moveRowAtIndexPath:(NSIndexPath *)indexPath toIndexPath:(NSIndexPath *)newIndexPath
 {
   ASDisplayNodeAssertMainThread();

examples/Kittens/Sample/KittenNode.mm

@@ -185,7 +185,6 @@ static const CGFloat kInnerPadding = 10.0f;
 - (void)toggleImageEnlargement
 {
   _isImageEnlarged = !_isImageEnlarged;
-  [self setNeedsLayout];
 }
 
 - (void)toggleNodesSwap

examples/Kittens/Sample/ViewController.m

@@ -118,11 +118,10 @@ static const NSInteger kMaxLitterSize = 100;        // max number of kitten cell
 - (void)tableView:(UITableView *)tableView didSelectRowAtIndexPath:(NSIndexPath *)indexPath
 {
   [_tableView deselectRowAtIndexPath:indexPath animated:YES];
-  [_tableView beginUpdates];
   // Assume only kitten nodes are selectable (see -tableView:shouldHighlightRowAtIndexPath:).
   KittenNode *node = (KittenNode *)[_tableView nodeForRowAtIndexPath:indexPath];
   [node toggleImageEnlargement];
-  [_tableView endUpdates];
+  [_tableView relayoutRowAtIndexPath:indexPath withRowAnimation:UITableViewRowAnimationAutomatic];
 }
 
 - (ASCellNode *)tableView:(ASTableView *)tableView nodeForRowAtIndexPath:(NSIndexPath *)indexPath