Fabric: Fixing crash in RCTScrollViewComponentView (2nd attempt)

shergin · facebook-github-bot · commit e7ef9921d3f9 · 2019-10-15T07:43:20.000-07:00
Summary: Seems a ScrollView sometimes calls the delegate in own destructor; and seems that in some configurations the delegate is also already destroyed at this point. I am not sure if this a bug in UIKit or not, but seems the fix is easy, we just have to clear the ScrollView's delegate on the delegate's deallocation. This issue is also looks similar: https://stackoverflow.com/questions/18778691/crash-on-exc-breakpoint-scroll-view/19011871 Changelog: [iOS] [Fixed] - Fixed crash in RCTScrollViewComponentView Reviewed By: sammy-SC Differential Revision: D17924429 fbshipit-source-id: 5727bca9f028e28f76f60304c187ee39eb6e1856
diff --git a/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm b/React/Fabric/Mounting/ComponentViews/ScrollView/RCTScrollViewComponentView.mm
@@ -85,7 +85,8 @@ - (instancetype)initWithFrame:(CGRect)frame
 
 - (void)dealloc
 {
-  [_scrollViewDelegateSplitter removeDelegate:self];
+  // This is not strictly necessary but that prevents a crash caused by a bug in UIKit.
+  _scrollView.delegate = nil;
 }
 
 #pragma mark - RCTComponentViewProtocol

Original file line number	Diff line number	Diff line change
`@@ -85,7 +85,8 @@ - (instancetype)initWithFrame:(CGRect)frame`
`85`	`85`
`86`	`86`	`- (void)dealloc`
`87`	`87`	`{`
`88`		`- [_scrollViewDelegateSplitter removeDelegate:self];`
	`88`	`+ // This is not strictly necessary but that prevents a crash caused by a bug in UIKit.`
	`89`	`+ _scrollView.delegate = nil;`
`89`	`90`	`}`
`90`	`91`
`91`	`92`	`#pragma mark - RCTComponentViewProtocol`