Merge pull request #1015 from facebook/CollectionTableLayers

Use _ASDisplayLayer for both ASTableView and ASCollectionView.  zeroContentInsets to fix UIKit.

AsyncDisplayKit/ASCollectionView.h

@@ -288,6 +288,16 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)clearFetchedData;
 
+/**
+ * Forces the .contentInset to be UIEdgeInsetsZero.
+ *
+ * @discussion By default, UIKit sets the top inset to the navigation bar height, even for horizontally
+ * scrolling views.  This can only be disabled by setting a property on the containing UIViewController,
+ * 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
 
 

AsyncDisplayKit/ASCollectionView.mm

@@ -17,6 +17,7 @@
 #import "ASInternalHelpers.h"
 #import "ASRangeController.h"
 #import "UICollectionViewLayout+ASConvenience.h"
+#import "_ASDisplayLayer.h"
 
 static const NSUInteger kASCollectionViewAnimationNone = UITableViewRowAnimationNone;
 static const ASSizeRange kInvalidSizeRange = {CGSizeZero, CGSizeZero};
@@ -113,6 +114,12 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 @implementation ASCollectionView
 
+// Using _ASDisplayLayer ensures things like -layout are properly forwarded to ASCollectionNode.
++ (Class)layerClass
+{
+  return [_ASDisplayLayer class];
+}
+
 #pragma mark -
 #pragma mark Lifecycle.
 
@@ -221,7 +228,6 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 - (void)reloadDataWithCompletion:(void (^)())completion
 {
-  ASDisplayNodeAssert(self.asyncDelegate, @"ASCollectionView's asyncDelegate property must be set.");
   ASPerformBlockOnMainThread(^{
     _superIsPendingDataLoad = YES;
     [super reloadData];
@@ -557,6 +563,10 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 
 - (void)layoutSubviews
 {
+  if (_zeroContentInsets) {
+    self.contentInset = UIEdgeInsetsZero;
+  }
+  
   if (! CGSizeEqualToSize(_maxSizeForNodesConstrainedSize, self.bounds.size)) {
     _maxSizeForNodesConstrainedSize = self.bounds.size;
     

AsyncDisplayKit/ASPagerNode.h

@@ -17,6 +17,8 @@
 - (ASCellNode *)pagerNode:(ASPagerNode *)pagerNode nodeAtIndex:(NSInteger)index;
 @end
 
+// WARNING: ASPagerNode is new in AsyncDisplayKit 1.9.4 and not yet widely tested.
+// Details of its API or behavior may change in future releases
 @interface ASPagerNode : ASCollectionNode
 
 // Configures a default horizontal, paging flow layout with 0 inter-item spacing.

AsyncDisplayKit/ASPagerNode.m

@@ -10,7 +10,8 @@
 #import "ASDelegateProxy.h"
 #import "ASDisplayNode+Subclasses.h"
 
-@interface ASPagerNode () <ASCollectionDataSource, ASCollectionViewDelegateFlowLayout, ASDelegateProxyInterceptor> {
+@interface ASPagerNode () <ASCollectionDataSource, ASCollectionViewDelegateFlowLayout, ASDelegateProxyInterceptor>
+{
   UICollectionViewFlowLayout *_flowLayout;
   ASPagerNodeProxy *_proxy;
   id <ASPagerNodeDataSource> _pagerDataSource;
@@ -46,25 +47,6 @@
   return self;
 }
 
-- (void)setDataSource:(id <ASPagerNodeDataSource>)pagerDataSource
-{
-  if (pagerDataSource != _pagerDataSource) {
-    _pagerDataSource = pagerDataSource;
-    _proxy = pagerDataSource ? [[ASPagerNodeProxy alloc] initWithTarget:pagerDataSource interceptor:self] : nil;
-    super.dataSource = (id <ASCollectionDataSource>)_proxy;
-  }
-}
-
-- (void)proxyTargetHasDeallocated:(ASDelegateProxy *)proxy
-{
-  [self setDataSource:nil];
-}
-
-- (id <ASPagerNodeDataSource>)dataSource
-{
-  return _pagerDataSource;
-}
-
 - (void)didLoad
 {
   [super didLoad];
@@ -77,6 +59,11 @@
   cv.showsHorizontalScrollIndicator = NO;
   cv.scrollsToTop = 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 preloadParams = { .leadingBufferScreenfuls = 2.0, .trailingBufferScreenfuls = 2.0 };
   ASRangeTuningParameters renderParams = { .leadingBufferScreenfuls = 1.0, .trailingBufferScreenfuls = 1.0 };
   [self setTuningParameters:preloadParams forRangeType:ASLayoutRangeTypePreload];
@@ -95,13 +82,14 @@
 
 - (ASCellNode *)collectionView:(ASCollectionView *)collectionView nodeForItemAtIndexPath:(NSIndexPath *)indexPath
 {
-  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load paging nodes");
-  return [_pagerDataSource pagerNode:self nodeAtIndex:indexPath.item];
+  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");
+  ASCellNode *pageNode = [_pagerDataSource pagerNode:self nodeAtIndex:indexPath.item];
+  return pageNode;
 }
 
 - (NSInteger)collectionView:(UICollectionView *)collectionView numberOfItemsInSection:(NSInteger)section
 {
-  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load paging nodes");
+  ASDisplayNodeAssert(_pagerDataSource != nil, @"ASPagerNode must have a data source to load nodes to display");
   return [_pagerDataSource numberOfPagesInPagerNode:self];
 }
 
@@ -110,4 +98,25 @@
   return ASSizeRangeMake(CGSizeZero, self.view.bounds.size);
 }
 
+#pragma mark - Data Source Proxy
+
+- (id <ASPagerNodeDataSource>)dataSource
+{
+  return _pagerDataSource;
+}
+
+- (void)setDataSource:(id <ASPagerNodeDataSource>)pagerDataSource
+{
+  if (pagerDataSource != _pagerDataSource) {
+    _pagerDataSource = pagerDataSource;
+    _proxy = pagerDataSource ? [[ASPagerNodeProxy alloc] initWithTarget:pagerDataSource interceptor:self] : nil;
+    super.dataSource = (id <ASCollectionDataSource>)_proxy;
+  }
+}
+
+- (void)proxyTargetHasDeallocated:(ASDelegateProxy *)proxy
+{
+  [self setDataSource:nil];
+}
+
 @end

AsyncDisplayKit/ASTableView.mm

@@ -18,6 +18,7 @@
 #import "ASLayout.h"
 #import "ASLayoutController.h"
 #import "ASRangeController.h"
+#import "_ASDisplayLayer.h"
 
 #import <CoreFoundation/CoreFoundation.h>
 
@@ -120,6 +121,12 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 @implementation ASTableView
 
+// Using _ASDisplayLayer ensures things like -layout are properly forwarded to ASTableNode.
++ (Class)layerClass
+{
+  return [_ASDisplayLayer class];
+}
+
 + (Class)dataControllerClass
 {
   return [ASChangeSetDataController class];
@@ -280,7 +287,6 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
 
 - (void)reloadDataWithCompletion:(void (^)())completion
 {
-  ASDisplayNodeAssert(self.asyncDelegate, @"ASTableView's asyncDelegate property must be set.");
   ASPerformBlockOnMainThread(^{
     [super reloadData];
   });