From 8cffc50d7da5773b696c86417239dc2baeecc558 Mon Sep 17 00:00:00 2001
From: Ryan Nystrom <rnystrom@instagram.com>
Date: Fri, 3 Nov 2017 11:24:29 -0700
Subject: [PATCH] Copy and nil block queue before executing #trivial

Summary:
Discovered in rnystrom/GitHawk#781 and introduced in d9a89c9b00aa1a9537a24d9affb6919f83065f65. Can't repro in unit test, but have obvious stack traces (see GitHawk issue) that collection is being mutated while enumerated.

No changelog since this is a new fix for 3.2.
Closes https://github.com/Instagram/IGListKit/pull/995

Reviewed By: manicakes

Differential Revision: D6206957

Pulled By: rnystrom

fbshipit-source-id: c42e3688d0f2b31693199f8015b5de48b7b3b9e6
---
 Source/IGListAdapter.m | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/Source/IGListAdapter.m b/Source/IGListAdapter.m
index 4c15a679..c6512ed8 100644
--- a/Source/IGListAdapter.m
+++ b/Source/IGListAdapter.m
@@ -749,10 +749,11 @@
 }
 
 - (void)exitBatchUpdates {
-    for (void (^block)(void) in _queuedCompletionBlocks) {
+    NSArray *blocks = [_queuedCompletionBlocks copy];
+    _queuedCompletionBlocks = nil;
+    for (void (^block)(void) in blocks) {
         block();
     }
-    _queuedCompletionBlocks = nil;
 }
 
 #pragma mark - UIScrollViewDelegate