From 620f83aae50f00e3e21987d73b2d42768ebe8bea Mon Sep 17 00:00:00 2001
From: Samuel Susla <samuelsusla@fb.com>
Date: Mon, 11 Nov 2019 02:59:37 -0800
Subject: [PATCH] Fix crash when accessing _viewRegistry

Summary:
Changelog: [internal] Fixes fabric specific crash

`_viewRegistry` is not thread safe and accessing it on another thread can cause a crash.
Calling it inside `RCTUnsafeExecuteOnMainQueueSync` shouldn't degrade performance because it is only used as a fallback.

Changelog: [Internal]

Reviewed By: rickhanlonii

Differential Revision: D18421789

fbshipit-source-id: 2adff434afe0a3c19318c95b051ee91ccf6293e5
---
 React/Modules/RCTUIManager.m | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/React/Modules/RCTUIManager.m b/React/Modules/RCTUIManager.m
index 53af9041faf..7b969de9327 100644
--- a/React/Modules/RCTUIManager.m
+++ b/React/Modules/RCTUIManager.m
@@ -335,7 +335,10 @@ static NSDictionary *deviceOrientationEventBody(UIDeviceOrientation orientation)
     return name;
   }
 
-  UIView *view = _viewRegistry[reactTag];
+  __block UIView *view;
+  RCTUnsafeExecuteOnMainQueueSync(^{
+    view = self->_viewRegistry[reactTag];
+  });
 
 #pragma clang diagnostic push
 #pragma clang diagnostic ignored "-Wundeclared-selector"