From 0e37bff7c1930dced2c4ebc8e07ffeb45c4cebce Mon Sep 17 00:00:00 2001
From: Ethan Nagel <eanagel@gmail.com>
Date: Wed, 24 Jun 2015 13:13:43 -0700
Subject: [PATCH] Revert to using a single NSIndexPath for the pending visible
 item

---
 AsyncDisplayKit/ASTableView.mm | 35 ++++++++++++++++++----------------
 1 file changed, 19 insertions(+), 16 deletions(-)

diff --git a/AsyncDisplayKit/ASTableView.mm b/AsyncDisplayKit/ASTableView.mm
index 080fe4f570..2288958d3c 100644
--- a/AsyncDisplayKit/ASTableView.mm
+++ b/AsyncDisplayKit/ASTableView.mm
@@ -125,7 +125,7 @@ static BOOL _isInterceptedSelector(SEL sel)
 
   ASBatchContext *_batchContext;
 
-  NSMutableSet *_pendingVisibleIndexPaths;
+  NSIndexPath *_pendingVisibleIndexPath;
 }
 
 @property (atomic, assign) BOOL asyncDataSourceLocked;
@@ -174,8 +174,6 @@ void ASPerformBlockWithoutAnimation(BOOL withoutAnimation, void (^block)()) {
 
   _leadingScreensForBatching = 1.0;
   _batchContext = [[ASBatchContext alloc] init];
-  
-  _pendingVisibleIndexPaths = [[NSMutableSet alloc] init];
 }
 
 - (instancetype)initWithFrame:(CGRect)frame style:(UITableViewStyle)style
@@ -433,7 +431,7 @@ void ASPerformBlockWithoutAnimation(BOOL withoutAnimation, void (^block)()) {
 
 - (void)tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath
 {
-  [_pendingVisibleIndexPaths addObject:indexPath];
+  _pendingVisibleIndexPath = indexPath;
 
   [_rangeController visibleNodeIndexPathsDidChangeWithScrollDirection:self.scrollDirection];
 
@@ -444,8 +442,8 @@ void ASPerformBlockWithoutAnimation(BOOL withoutAnimation, void (^block)()) {
 
 - (void)tableView:(UITableView *)tableView didEndDisplayingCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath*)indexPath
 {
-  if ([_pendingVisibleIndexPaths containsObject:indexPath]) {
-    [_pendingVisibleIndexPaths removeObject:indexPath];
+  if ([_pendingVisibleIndexPath isEqual:indexPath]) {
+    _pendingVisibleIndexPath = nil;
   }
 
   [_rangeController visibleNodeIndexPathsDidChangeWithScrollDirection:self.scrollDirection];
@@ -519,15 +517,20 @@ void ASPerformBlockWithoutAnimation(BOOL withoutAnimation, void (^block)()) {
 {
   ASDisplayNodeAssertMainThread();
 
-  NSMutableSet *visibleIndexPaths = [NSMutableSet setWithArray:[self indexPathsForVisibleRows]];
-  
-  // First, remove any index paths we're tracking that UIKit has now proven it can remember :)
-  [_pendingVisibleIndexPaths minusSet:visibleIndexPaths];
-  
-  // Next, add all remaining index paths that we know should be visible (from willDisplayCell) but are not in the set.
-  [visibleIndexPaths unionSet:_pendingVisibleIndexPaths];
-  
-  return visibleIndexPaths.allObjects;
+  NSArray *visibleIndexPaths = self.indexPathsForVisibleRows;
+
+  if ( _pendingVisibleIndexPath ) {
+    NSMutableSet *indexPaths = [NSMutableSet setWithArray:self.indexPathsForVisibleRows];
+
+    if ( [indexPaths containsObject:_pendingVisibleIndexPath]) {
+      _pendingVisibleIndexPath = nil; // once it has shown up in visibleIndexPaths, we can stop tracking it
+    } else {
+      [indexPaths addObject:_pendingVisibleIndexPath];
+      visibleIndexPaths = indexPaths.allObjects;
+    }
+  }
+
+  return visibleIndexPaths;
 }
 
 - (NSArray *)rangeController:(ASRangeController *)rangeController nodesAtIndexPaths:(NSArray *)indexPaths
@@ -544,7 +547,7 @@ void ASPerformBlockWithoutAnimation(BOOL withoutAnimation, void (^block)()) {
 - (void)rangeController:(ASRangeController *)rangeController didInsertNodesAtIndexPaths:(NSArray *)indexPaths withAnimationOption:(ASDataControllerAnimationOptions)animationOption
 {
   ASDisplayNodeAssertMainThread();
-  
+
   BOOL preventAnimation = animationOption == UITableViewRowAnimationNone;
   ASPerformBlockWithoutAnimation(preventAnimation, ^{
     [super insertRowsAtIndexPaths:indexPaths withRowAnimation:(UITableViewRowAnimation)animationOption];