[WIP] Trigger new batch fetch for collection view after layout transitions (#1697)

[Table / Collection] Trigger new batch fetch after programmatic scrolls, or layout transitions.

AsyncDisplayKit/ASCollectionView.mm

@@ -1002,6 +1002,7 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
 - (NSArray *)visibleNodeIndexPathsForRangeController:(ASRangeController *)rangeController
 {
   ASDisplayNodeAssertMainThread();
+  
   // Calling visibleNodeIndexPathsForRangeController: will trigger UIKit to call reloadData if it never has, which can result
   // in incorrect layout if performed at zero size.  We can use the fact that nothing can be visible at zero size to return fast.
   BOOL isZeroSized = CGRectEqualToRect(self.bounds, CGRectZero);
@@ -1065,6 +1066,11 @@ static NSString * const kCellReuseIdentifier = @"_ASCollectionViewCell";
   _performingBatchUpdates = NO;
 }
 
+- (void)didCompleteUpdatesInRangeController:(ASRangeController *)rangeController
+{
+  [self _checkForBatchFetching];
+}
+
 - (void)rangeController:(ASRangeController *)rangeController didInsertNodes:(NSArray *)nodes atIndexPaths:(NSArray *)indexPaths withAnimationOptions:(ASDataControllerAnimationOptions)animationOptions
 {
   ASDisplayNodeAssertMainThread();

AsyncDisplayKit/ASTableView.mm

@@ -968,6 +968,11 @@ static NSString * const kCellReuseIdentifier = @"_ASTableViewCell";
   }
 }
 
+- (void)didCompleteUpdatesInRangeController:(ASRangeController *)rangeController
+{
+  [self _checkForBatchFetching];
+}
+
 - (void)rangeController:(ASRangeController *)rangeController didInsertNodes:(NSArray *)nodes atIndexPaths:(NSArray *)indexPaths withAnimationOptions:(ASDataControllerAnimationOptions)animationOptions
 {
   ASDisplayNodeAssertMainThread();

AsyncDisplayKit/Details/ASRangeController.h

@@ -146,6 +146,13 @@ NS_ASSUME_NONNULL_BEGIN
  */
 - (void)rangeController:(ASRangeController * )rangeController didEndUpdatesAnimated:(BOOL)animated completion:(void (^)(BOOL))completion;
 
+/**
+ * Completed updates to cell node addition and removal.
+ *
+ * @param rangeController Sender.
+ */
+- (void)didCompleteUpdatesInRangeController:(ASRangeController *)rangeController;
+
 /**
  * Called for nodes insertion.
  *

AsyncDisplayKit/Details/ASRangeController.mm

@@ -333,6 +333,7 @@ static UIApplicationState __ApplicationState = UIApplicationStateActive;
   [modifiedIndexPaths sortUsingSelector:@selector(compare:)];
   NSLog(@"Range update complete; modifiedIndexPaths: %@", [self descriptionWithIndexPaths:modifiedIndexPaths]);
 #endif
+  [_delegate didCompleteUpdatesInRangeController:self];
 }
 
 #pragma mark - Notification observers