Specific crash since iOS 13.2

Number:rdar://FB7543829 Date Originated:20/01/2020
Status:Open Resolved:
Product:UIKit Product Version:
Classification:Application Crash Reproducible:
Since the launch of iOS 13.2, we've been seeing a steadily rising level of a specific crash. This crash seems to be completely inside UIKit, although some action in our app is obviously "triggering" it.

Of course, I’ve attached a few crash report files.

But also there is a top part of call-stack:

-[UIView(Internal) _addSubview:positioned:relativeTo:]
-[UIInputWindowController changeToInputViewSet:]
-[UIInputWindowController setInputViewSet:]
+[UIView(Animation) performWithoutAnimation:]
-[UIInputWindowController setInputViewSet:]
-[UIInputWindowController performOperations:withAnimationStyle:]
-[UIInputResponderController setKeyWindowSceneInputViews:animationStyle:]
-[UIInputResponderController setInputViews:animationStyle:]
-[UIInputResponderController forceOrderOutAutomaticExceptAccessoryView]
-[UIKeyboardAutomatic willResume:]
-[NSNotificationCenter addObserver:selector:name:object:]
-[_CFXNotificationRegistrar find:object:observer:enumerator:]
-[NSNotificationCenter postNotificationName:object:userInfo:]
-[UIApplication _sendWillEnterForegroundCallbacks]

I also have found an already started discussion at https://forums.developer.apple.com/thread/125447


Easy steps to reproduce: 
1) Open keyboard settings and enable predictive text and auto-correction features. It’s necessary for reproducing the crash. 2) Run Bumble app and open any chat with another user. 3) Type something till the moment when text replacement variants appear, and the text you entered becomes selected. 4) Switch to the application launcher and kill the Bumble application as fast as possible.

The crash happens whilst the application is terminating.

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