UIViewControllerHierarchyInconsistency

Description

The app has been inactive for around 2 min on a “enter pin code page” leading to that the iPhone has been locked. If the user then unlocks the phone, enter the pin code and press the login button, the app then crashes.

After setting enabledScreen(false), I have not been able to reproduce a crash.

Exception from Bugsnag:

UIViewControllerHierarchyInconsistency: child view controller:<RNScreensViewController: 0x126d2ce00> should have parent view controller:(null) but actual parent is:<UIViewController: 0x125e2a7d0>

0  CoreFoundation   ___exceptionPreprocess
1  libobjc.A.dylib  _objc_exception_throw
2  CoreFoundation   +[NSException raise:format:]
3  UIKitCore        -[UIView(Hierarchy) _associatedViewControllerForwardsAppearanceCallbacks:performHierarchyCheck:isRoot:]
4  UIKitCore        -[UIView(Hierarchy) _willMoveToWindow:withAncestorView:]
5  UIKitCore        -[UIView(Internal) _addSubview:positioned:relativeTo:]
6  UIKitCore        ___67-[UIViewControllerBuiltinTransitionViewAnimator animateTransition:]_block_invoke_2
7  UIKitCore        +[UIView(Animation) performWithoutAnimation:]
8  UIKitCore        ___67-[UIViewControllerBuiltinTransitionViewAnimator animateTransition:]_block_invoke
9  UIKitCore        +[UIView _setupAnimationWithDuration:delay:view:options:factory:animations:start:animationStateGenerator:completion:]
10 UIKitCore        +[UIView(UIViewAnimationWithBlocks) animateWithDuration:delay:options:animations:completion:]
11 UIKitCore        -[UIViewControllerBuiltinTransitionViewAnimator animateTransition:]
12 UIKitCore        ____UIViewControllerTransitioningRunCustomTransition_block_invoke_2
13 UIKitCore        +[UIInputResponderController _pinInputViewsForInputResponderController:onBehalfOfResponder:duringBlock:]
14 UIKitCore        ____UIViewControllerTransitioningRunCustomTransition_block_invoke.663
15 UIKitCore        +[UIView(Animation) _setAlongsideAnimations:toRunByEndOfBlock:]
16 UIKitCore        __UIViewControllerTransitioningRunCustomTransition
17 UIKitCore        ___56-[UIPresentationController runTransitionForCurrentState]_block_invoke.491
18 UIKitCore        -[_UIAfterCACommitBlock run]
19 UIKitCore        __runAfterCACommitDeferredBlocks
20 UIKitCore        __cleanUpAfterCAFlushAndRunDeferredBlocks
21 UIKitCore        __afterCACommitHandler
22 CoreFoundation   ___CFRUNLOOP_IS_CALLING_OUT_TO_AN_OBSERVER_CALLBACK_FUNCTION__
23 CoreFoundation   ___CFRunLoopDoObservers
24 CoreFoundation   ___CFRunLoopRun
25 CoreFoundation   _CFRunLoopRunSpecific
26 GraphicsServices _GSEventRunModal
27 UIKitCore        -[UIApplication _run]
28 UIKitCore        _UIApplicationMain

Screenshots

This is the “breadcrumb” from Bugsnag:

Package versions

• React: 17.0.1
• React Native: 0.64.1
• React Native Screens: 3.0.0

[WoLewicki]

I debugged it and it seems like there is a race condition between Modal and Screen view controllers being attached/detached. I am not sure if we can do anything about it since it comes from asynchronous behaviors of these events. The solution to this is probably adding setTimeout for showing the modal in the new screen, so first the proper native hierarchy of view controllers is established, something like this:

const CrashScreen: FC = () => {
  const [showModal, setShowModal] = useState(false);

  useEffect(() => {
    setTimeout(() => {
      setShowModal(true);
    }, 0);
  }, []);

  return (
    <View style={styles.container}>
      <Text>Crash screen</Text>
      <Modal visible={showModal}>
        <View style={styles.container}>
          <Text>Loading</Text>
        </View>
      </Modal>
    </View>
  );
};

Can you check if it resolves the issue?

[WoLewicki]

I think it is only needed if you open a screen with the modal shown from the beginning since then react-native-screens also changes the native controller hierarchy.