Move most of the batch fetching logic to a central place for ASTableView and ASCollectionView usage

AsyncDisplayKit/Private/ASBatchFetching.m

@@ -8,23 +8,31 @@
 
 #import "ASBatchFetching.h"
 
-BOOL ASDisplayShouldFetchBatchForContext(ASBatchContext *context,
-                                    ASScrollDirection scrollDirection,
-                                    CGRect bounds,
-                                    CGSize contentSize,
-                                    CGPoint targetOffset,
-                                    CGFloat leadingScreens) {
-  // do not allow fetching if a batch is already in-flight and hasn't been completed or cancelled
+BOOL ASDisplayShouldFetchBatchForScrollView(UIScrollView<ASBatchFetchingScrollView> *scrollView, ASScrollDirection scrollDirection, CGPoint contentOffset)
+{
+
+  // Don't fetch if the scroll view does not allow
+  if (![scrollView canBatchFetch]) {
+    return NO;
+  }
+  
+  // Check if we should batch fetch
+  ASBatchContext *context = scrollView.batchContext;
+  CGRect bounds = scrollView.bounds;
+  CGSize contentSize = scrollView.contentSize;
+  CGFloat leadingScreens = scrollView.leadingScreensForBatching;
+  
+  // Do not allow fetching if a batch is already in-flight and hasn't been completed or cancelled
   if ([context isFetching]) {
     return NO;
   }
 
-  // only Down and Right scrolls are currently supported (tail loading)
+  // Only Down and Right scrolls are currently supported (tail loading)
   if (!ASScrollDirectionContainsDown(scrollDirection) && !ASScrollDirectionContainsRight(scrollDirection)) {
     return NO;
   }
 
-  // no fetching for null states
+  // No fetching for null states
   if (leadingScreens <= 0.0 || CGRectEqualToRect(bounds, CGRectZero)) {
     return NO;
   }
@@ -33,11 +41,11 @@ BOOL ASDisplayShouldFetchBatchForContext(ASBatchContext *context,
 
   if (ASScrollDirectionContainsDown(scrollDirection)) {
     viewLength = bounds.size.height;
-    offset = targetOffset.y;
+    offset = contentOffset.y;
     contentLength = contentSize.height;
   } else { // horizontal / right
     viewLength = bounds.size.width;
-    offset = targetOffset.x;
+    offset = contentOffset.x;
     contentLength = contentSize.width;
   }