From 4b8d07ebf367445732960fe47be0c790df0f7e5a Mon Sep 17 00:00:00 2001
From: Valentin Shergin <shergin@fb.com>
Date: Mon, 24 Jun 2019 18:29:17 -0700
Subject: [PATCH] Fabric: Fixed another crash in RCTImageComponentView (nulled
 event emitter)

Summary: This fixes a crash happened in Image component caused by a race between recycling a component and image loading event are being delivered asynchronously.

Reviewed By: mdvacca

Differential Revision: D15977418

fbshipit-source-id: ac6f4b3d2b995af2afd56e551380a32d0f14ab15
---
 .../ComponentViews/Image/RCTImageComponentView.mm | 15 +++++++++++++++
 1 file changed, 15 insertions(+)

diff --git a/React/Fabric/Mounting/ComponentViews/Image/RCTImageComponentView.mm b/React/Fabric/Mounting/ComponentViews/Image/RCTImageComponentView.mm
index 6d579e16452..3620291ade4 100644
--- a/React/Fabric/Mounting/ComponentViews/Image/RCTImageComponentView.mm
+++ b/React/Fabric/Mounting/ComponentViews/Image/RCTImageComponentView.mm
@@ -125,6 +125,13 @@
 
 - (void)didReceiveImage:(UIImage *)image fromObserver:(void *)observer
 {
+  if (!_eventEmitter) {
+    // Notifications are delivered asynchronously and might arrive after the view is already recycled.
+    // In the future, we should incorporate an `EventEmitter` into a separate object owned by `ImageRequest` or `State`.
+    // See for more info: T46311063.
+    return;
+  }
+
   std::static_pointer_cast<const ImageEventEmitter>(_eventEmitter)->onLoad();
 
   const auto &imageProps = *std::static_pointer_cast<const ImageProps>(_props);
@@ -153,11 +160,19 @@
 
 - (void)didReceiveProgress:(float)progress fromObserver:(void *)observer
 {
+  if (!_eventEmitter) {
+    return;
+  }
+
   std::static_pointer_cast<const ImageEventEmitter>(_eventEmitter)->onProgress(progress);
 }
 
 - (void)didReceiveFailureFromObserver:(void *)observer
 {
+  if (!_eventEmitter) {
+    return;
+  }
+
   std::static_pointer_cast<const ImageEventEmitter>(_eventEmitter)->onError();
 }