Merge branch 'master' into update-objc

Conflicts:
	AsyncDisplayKit/ASCollectionView.h
	AsyncDisplayKit/ASDisplayNode.h
	AsyncDisplayKit/Details/ASDataController.h
	AsyncDisplayKit/Details/UIView+ASConvenience.h
	AsyncDisplayKit/Layout/ASLayoutSpec.h

AsyncDisplayKit/ASCollectionView.h

@@ -17,6 +17,7 @@
 @class ASCellNode;
 @protocol ASCollectionViewDataSource;
 @protocol ASCollectionViewDelegate;
+@protocol ASCollectionViewLayoutInspecting;
 
 NS_ASSUME_NONNULL_BEGIN
 
@@ -64,7 +65,7 @@ NS_ASSUME_NONNULL_BEGIN
  *
  * @param asyncDataFetchingEnabled Enable the data fetching in async mode.
  *
- * @discussion If asyncDataFetching is enabled, the `AScollectionView` will fetch data through `collectionView:numberOfRowsInSection:` and
+ * @discussion If asyncDataFetching is enabled, the `ASCollectionView` will fetch data through `collectionView:numberOfRowsInSection:` and
  * `collectionView:nodeForRowAtIndexPath:` in async mode from background thread. Otherwise, the methods will be invoked synchronically
  * from calling thread.
  * Enabling asyncDataFetching could avoid blocking main thread for `ASCellNode` allocation, which is frequently reported issue for
@@ -81,6 +82,18 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @property (nonatomic, assign) CGFloat leadingScreensForBatching;
 
+/**
+ * Optional introspection object for the collection view's layout.
+ *
+ * @discussion Since supplementary and decoration views are controlled by the collection view's layout, this object
+ * is used as a bridge to provide information to the internal data controller about the existence of these views and
+ * their associated index paths. For collection views using `UICollectionViewFlowLayout`, a default inspector
+ * implementation `ASCollectionViewFlowLayoutInspector` is created and set on this property by default. Custom
+ * collection view layout subclasses will need to provide their own implementation of an inspector object for their
+ * supplementary views to be compatible with `ASCollectionView`'s supplementary node support.
+ */
+@property (nonatomic, weak) id<ASCollectionViewLayoutInspecting> layoutInspector;
+
 /**
  *  Perform a batch of updates asynchronously, optionally disabling all animations in the batch. This method must be called from the main thread. 
  *  The asyncDataSource must be updated to reflect the changes before the update block completes.
@@ -120,6 +133,26 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)reloadData;
 
+/**
+ * Reload everything from scratch entirely on the main thread, destroying the working range and all cached nodes.
+ *
+ * @warning This method is substantially more expensive than UICollectionView's version and will block the main thread
+ * while all the cells load.
+ */
+- (void)reloadDataImmediately;
+
+/**
+ * Registers the given kind of supplementary node for use in creating node-backed supplementary views.
+ *
+ * @param kind The kind of supplementary node that will be requested through the data source.
+ *
+ * @discussion Use this method to register support for the use of supplementary nodes in place of the default
+ * `registerClass:forSupplementaryViewOfKind:withReuseIdentifier:` and `registerNib:forSupplementaryViewOfKind:withReuseIdentifier:`
+ * methods. This method will register an internal backing view that will host the contents of the supplementary nodes
+ * returned from the data source.
+ */
+- (void)registerSupplementaryNodeOfKind:(NSString *)elementKind;
+
 /**
  * Inserts one or more sections.
  *
@@ -192,6 +225,16 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)reloadItemsAtIndexPaths:(NSArray<NSIndexPath *> *)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.
  *
@@ -273,6 +316,15 @@ NS_ASSUME_NONNULL_BEGIN
 
 @optional
 
+/**
+ * Asks the collection view to provide a supplementary node to display in the collection view.
+ *
+ * @param collectionView An object representing the collection view requesting this information.
+ * @param kind           The kind of supplementary node to provide.
+ * @param indexPath      The index path that specifies the location of the new supplementary node.
+ */
+- (ASCellNode *)collectionView:(ASCollectionView *)collectionView nodeForSupplementaryElementOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
+
 /**
  * Provides the constrained size range for measuring the node at the index path.
  *
@@ -343,18 +395,37 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (BOOL)shouldBatchFetchForCollectionView:(ASCollectionView *)collectionView;
 
+@end
+
+/**
+ * Defines methods that let you coordinate with a `UICollectionViewFlowLayout` in combination with an `ASCollectionView`.
+ */
+@protocol ASCollectionViewDelegateFlowLayout <ASCollectionViewDelegate>
+
+@optional
+
 /**
  * Passthrough support to UICollectionViewDelegateFlowLayout sectionInset behavior.
  *
  * @param collectionView The sender.
  * @param collectionViewLayout The layout object requesting the information.
- * #param section The index number of the section whose insets are needed.
+ * @param section The index number of the section whose insets are needed.
  *
  * @discussion The same rules apply as the UICollectionView implementation, but this can also be used without a UICollectionViewFlowLayout.
  * https://developer.apple.com/library/ios/documentation/UIKit/Reference/UICollectionViewDelegateFlowLayout_protocol/index.html#//apple_ref/occ/intfm/UICollectionViewDelegateFlowLayout/collectionView:layout:insetForSectionAtIndex:
  *
  */
-- (UIEdgeInsets)collectionView:(UICollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section;
+- (UIEdgeInsets)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout insetForSectionAtIndex:(NSInteger)section;
+
+/**
+ * Asks the delegate for the size of the header in the specified section.
+ */
+- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForHeaderInSection:(NSInteger)section;
+
+/**
+ * Asks the delegate for the size of the footer in the specified section.
+ */
+- (CGSize)collectionView:(ASCollectionView *)collectionView layout:(UICollectionViewLayout *)collectionViewLayout referenceSizeForFooterInSection:(NSInteger)section;
 
 @end