From bb89f70510061646056211b6da8ca07c0f4433ea Mon Sep 17 00:00:00 2001
From: Zhisheng Huang <zsh@fb.com>
Date: Fri, 14 Feb 2020 15:27:12 -0800
Subject: [PATCH] Fix a bug in IGListBindingSingleSectionController for
 displayingCell setting

Summary:
When a section/cell is reloaded, UICollectionView actually calls:

1/ WillDisplay (new cell)
2/ DidEndDisplay (old cell)

So if we set `_displayingCell` in willDisplay call, then set it to nil in didEndDisplay, we would just have a nil cell. Thus we need to make sure the cell in `didEndDisplay` match with the previous `_displayCell` to avoid nil-ing ourselves out.

Reviewed By: alanzeino

Differential Revision: D19906734

fbshipit-source-id: 5217908ae99d488a2af5ff3f90ef8e021774acda
---
 Source/IGListKit/IGListBindingSingleSectionController.m | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/Source/IGListKit/IGListBindingSingleSectionController.m b/Source/IGListKit/IGListBindingSingleSectionController.m
index bcffa33c..f57bdc55 100644
--- a/Source/IGListKit/IGListBindingSingleSectionController.m
+++ b/Source/IGListKit/IGListBindingSingleSectionController.m
@@ -72,7 +72,9 @@
 
 - (void)listAdapter:(nonnull IGListAdapter *)listAdapter didEndDisplayingSectionController:(nonnull IGListSectionController *)sectionController cell:(nonnull UICollectionViewCell *)cell atIndex:(NSInteger)index {
     IGParameterAssert(index == 0);
-    _displayingCell = nil;
+    if (cell == _displayingCell) {
+        _displayingCell = nil;
+    }
 }
 
 #pragma mark - IGListSectionController Overrides