Update data source protocols to make synchronous node creation api methods optional.

AsyncDisplayKit/ASCollectionView.h

@@ -340,6 +340,8 @@ NS_ASSUME_NONNULL_BEGIN
 #define ASCollectionViewDataSource ASCollectionDataSource
 @protocol ASCollectionDataSource <ASCommonCollectionViewDataSource, NSObject>
 
+@optional
+
 /**
  * Similar to -collectionView:cellForItemAtIndexPath:.
  *
@@ -353,10 +355,9 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (ASCellNode *)collectionView:(ASCollectionView *)collectionView nodeForItemAtIndexPath:(NSIndexPath *)indexPath;
 
-
-@optional
-
 /**
+ * Similar to -collectionView:nodeForItemAtIndexPath:
+ * This method takes precedence over collectionView:nodeForItemAtIndexPath: if implemented.
  *
  * @param collectionView The sender.
  *

AsyncDisplayKit/ASCollectionView.mm

@@ -294,7 +294,6 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
   // super.dataSource in this case because calls to ASCollectionViewProxy will start failing and cause crashes.
 
   super.dataSource = nil;
-  
   if (asyncDataSource == nil) {
     _asyncDataSource = nil;
     _proxyDataSource = _isDeallocating ? nil : [[ASCollectionViewProxy alloc] initWithTarget:nil interceptor:self];
@@ -305,6 +304,9 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
     _proxyDataSource = [[ASCollectionViewProxy alloc] initWithTarget:_asyncDataSource interceptor:self];
     _asyncDataSourceImplementsConstrainedSizeForNode = [_asyncDataSource respondsToSelector:@selector(collectionView:constrainedSizeForNodeAtIndexPath:)];
     _asyncDataSourceImplementsNodeBlockForItemAtIndexPath = [_asyncDataSource respondsToSelector:@selector(collectionView:nodeBlockForItemAtIndexPath:)];
+
+    // Data-source must implement collectionView:nodeForItemAtIndexPath: or collectionView:nodeBlockForItemAtIndexPath:
+    ASDisplayNodeAssertTrue(_asyncDataSourceImplementsNodeBlockForItemAtIndexPath || [_asyncDataSource respondsToSelector:@selector(collectionView:nodeForItemAtIndexPath:)]);
   }
   
   super.dataSource = (id<UICollectionViewDataSource>)_proxyDataSource;
@@ -678,19 +680,6 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 #pragma mark - ASDataControllerSource
 
-- (ASCellNode *)dataController:(ASDataController *)dataController nodeAtIndexPath:(NSIndexPath *)indexPath
-{
-  ASCellNode *node = [_asyncDataSource collectionView:self nodeForItemAtIndexPath:indexPath];
-  [node enterHierarchyState:ASHierarchyStateRangeManaged];
-  
-  ASDisplayNodeAssert([node isKindOfClass:ASCellNode.class], @"invalid node class, expected ASCellNode");
-  if (node.layoutDelegate == nil) {
-    node.layoutDelegate = self;
-  }
-  return node;
-}
-
-
 - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAtIndexPath:(NSIndexPath *)indexPath
 {
   if (!_asyncDataSourceImplementsNodeBlockForItemAtIndexPath) {

AsyncDisplayKit/ASPagerNode.h

@@ -10,15 +10,44 @@
 
 @class ASPagerNode;
 @protocol ASPagerNodeDataSource <NSObject>
-// This method replaces -collectionView:numberOfItemsInSection:
-- (NSInteger)numberOfPagesInPagerNode:(ASPagerNode *)pagerNode;
 
-// This method replaces -collectionView:nodeForItemAtIndexPath:
-- (ASCellNode *)pagerNode:(ASPagerNode *)pagerNode nodeAtIndex:(NSInteger)index;
+/**
+ * This method replaces -collectionView:numberOfItemsInSection:
+ *
+ * @param pagerNode The sender.
+ *
+ *
+ * @returns The total number of pages that can display in the pagerNode.
+ */
+- (NSInteger)numberOfPagesInPagerNode:(ASPagerNode *)pagerNode;
 
 @optional
 
-// This method replaces -collectionView:nodeBlockForItemAtIndexPath:
+/**
+ * This method replaces -collectionView:nodeForItemAtIndexPath:
+ *
+ * @param pagerNode The sender.
+ *
+ * @param index The index of the requested node.
+ *
+ * @returns a node for display at this index. This will be called on the main thread and should
+ *   not implement reuse (it will be called once per row).  Unlike UICollectionView's version,
+ *   this method is not called when the row is about to display.
+ */
+- (ASCellNode *)pagerNode:(ASPagerNode *)pagerNode nodeAtIndex:(NSInteger)index;
+
+/**
+ * This method replaces -collectionView:nodeBlockForItemAtIndexPath:
+ * This method takes precedence over pagerNode:nodeAtIndex: if implemented.
+ *
+ * @param pagerNode The sender.
+ *
+ * @param index The index of the requested node.
+ *
+ * @returns a block that creates the node for display at this index.
+ *   Must be thread-safe (can be called on the main thread or a background
+ *   queue) and should not implement reuse (it will be called once per row).
+ */
 - (ASCellNodeBlock)pagerNode:(ASPagerNode *)pagerNode nodeBlockAtIndex:(NSInteger)index;
 
 @end

AsyncDisplayKit/ASPagerNode.m

@@ -83,13 +83,6 @@
 
 #pragma mark - ASCollectionViewDataSource
 
-- (ASCellNode *)collectionView:(ASCollectionView *)collectionView nodeForItemAtIndexPath:(NSIndexPath *)indexPath
-{
-  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");
-  ASCellNode *pageNode = [_pagerDataSource pagerNode:self nodeAtIndex:indexPath.item];
-  return pageNode;
-}
-
 - (ASCellNodeBlock)collectionView:(ASCollectionView *)collectionView nodeBlockForItemAtIndexPath:(NSIndexPath *)indexPath
 {
   ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");
@@ -123,7 +116,10 @@
   if (pagerDataSource != _pagerDataSource) {
     _pagerDataSource = pagerDataSource;
     _pagerDataSourceImplementsNodeBlockAtIndex = [_pagerDataSource respondsToSelector:@selector(pagerNode:nodeBlockAtIndex:)];
+    // Data source must implement pagerNode:nodeBlockAtIndex: or pagerNode:nodeAtIndex:
+    ASDisplayNodeAssertTrue(_pagerDataSourceImplementsNodeBlockAtIndex || [_pagerDataSource respondsToSelector:@selector(pagerNode:nodeAtIndex:)]);
     _proxy = pagerDataSource ? [[ASPagerNodeProxy alloc] initWithTarget:pagerDataSource interceptor:self] : nil;
+    
     super.dataSource = (id <ASCollectionDataSource>)_proxy;
   }
 }

AsyncDisplayKit/ASTableView.h

@@ -315,6 +315,8 @@ NS_ASSUME_NONNULL_BEGIN
  */
 @protocol ASTableDataSource <ASCommonTableViewDataSource, NSObject>
 
+@optional
+
 /**
  * Similar to -tableView:cellForRowAtIndexPath:.
  *
@@ -327,11 +329,10 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (ASCellNode *)tableView:(ASTableView *)tableView nodeForRowAtIndexPath:(NSIndexPath *)indexPath;
 
-@optional
 
 /**
- * Similar to -tableView:nodeForRowAtIndexPath:.
- *
+ * Similar to -tableView:nodeForRowAtIndexPath:
+ * This method takes precedence over tableView:nodeForRowAtIndexPath: if implemented.
  * @param tableView The sender.
  *
  * @param indexPath The index path of the requested node.

AsyncDisplayKit/ASTableView.mm

@@ -111,6 +111,7 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
   BOOL _ignoreNodesConstrainedWidthChange;
   BOOL _queuedNodeHeightUpdate;
   BOOL _isDeallocating;
+  BOOL _dataSourceImplementsNodeBlockForRowAtIndexPath;
 }
 
 @property (atomic, assign) BOOL asyncDataSourceLocked;
@@ -256,8 +257,12 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
   if (asyncDataSource == nil) {
     _asyncDataSource = nil;
     _proxyDataSource = _isDeallocating ? nil : [[ASTableViewProxy alloc] initWithTarget:nil interceptor:self];
+    _dataSourceImplementsNodeBlockForRowAtIndexPath = NO;
   } else {
     _asyncDataSource = asyncDataSource;
+    _dataSourceImplementsNodeBlockForRowAtIndexPath = [_asyncDataSource respondsToSelector:@selector(tableView:nodeBlockForRowAtIndexPath:)];
+    // Data source must implement tableView:nodeBlockForRowAtIndexPath: or tableView:nodeForRowAtIndexPath:
+    ASDisplayNodeAssertTrue(_dataSourceImplementsNodeBlockForRowAtIndexPath || [_asyncDataSource respondsToSelector:@selector(tableView:nodeForRowAtIndexPath:)]);
     _proxyDataSource = [[ASTableViewProxy alloc] initWithTarget:_asyncDataSource interceptor:self];
   }
   
@@ -862,18 +867,6 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 #pragma mark - ASDataControllerDelegate
 
-- (ASCellNode *)dataController:(ASDataController *)dataController nodeAtIndexPath:(NSIndexPath *)indexPath
-{
-  ASCellNode *node = [_asyncDataSource tableView:self nodeForRowAtIndexPath:indexPath];
-  [node enterHierarchyState:ASHierarchyStateRangeManaged];
-  
-  ASDisplayNodeAssert([node isKindOfClass:ASCellNode.class], @"invalid node class, expected ASCellNode");
-  if (node.layoutDelegate == nil) {
-    node.layoutDelegate = self;
-  }
-  return node;
-}
-
 - (ASCellNodeBlock)dataController:(ASDataController *)dataController nodeBlockAtIndexPath:(NSIndexPath *)indexPath {
   if (![_asyncDataSource respondsToSelector:@selector(tableView:nodeBlockForRowAtIndexPath:)]) {
     ASCellNode *node = [_asyncDataSource tableView:self nodeForRowAtIndexPath:indexPath];

AsyncDisplayKit/Details/ASCollectionDataController.h

@@ -17,8 +17,6 @@
 
 @protocol ASCollectionDataControllerSource <ASDataControllerSource>
 
-- (ASCellNode *)dataController:(ASCollectionDataController *)dataController supplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
-
 /**
  The constrained size range for layout.
  */
@@ -32,6 +30,8 @@
 
 @optional
 
+- (ASCellNode *)dataController:(ASCollectionDataController *)dataController supplementaryNodeOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
+
 - (ASCellNodeBlock)dataController:(ASCollectionDataController *)dataController supplementaryNodeBlockOfKind:(NSString *)kind atIndexPath:(NSIndexPath *)indexPath;
 
 @end

AsyncDisplayKit/Details/ASCollectionDataController.mm

@@ -255,6 +255,8 @@
 {
   [super setDataSource:dataSource];
   _dataSourceImplementsSupplementaryNodeBlockOfKindAtIndexPath = [self.collectionDataSource respondsToSelector:@selector(dataController:supplementaryNodeBlockOfKind:atIndexPath:)];
+
+  ASDisplayNodeAssertTrue(_dataSourceImplementsSupplementaryNodeBlockOfKindAtIndexPath || [self.collectionDataSource respondsToSelector:@selector(dataController:supplementaryNodeOfKind:atIndexPath:)]);
 }
 
 @end

AsyncDisplayKit/Details/ASDataController.h

@@ -35,11 +35,6 @@ FOUNDATION_EXPORT NSString * const ASDataControllerRowNodeKind;
 
 @protocol ASDataControllerSource <NSObject>
 
-/**
- Fetch the ASCellNode for specific index path.
- */
-- (ASCellNode *)dataController:(ASDataController *)dataController nodeAtIndexPath:(NSIndexPath *)indexPath;
-
 /**
  Fetch the ASCellNode block for specific index path. This block should return the ASCellNode for the specified index path.
  */