Open Radar

 
*** Description ***

When any app calls into drawViewHierarchyInRect:afterScreenUpdates: and `afterScreenUpdates` is YES, the app afterwards exhibits visual bugs with the iOS multi-finger system gestures (five finger pinch to background app, or four finger swipe to move between apps, etc). Specifically, a black frame can be seen when swiping between apps or pinching away to the home screen.

If afterScreenUpdates is NO or renderInContext: etc. is used, the issue does not occur.

This is reproducible in a template iOS project using Apple's own example code for drawViewHierarchyInRect:afterScreenUpdates.

*** Repro Steps ***

1. Create a new iOS app from a default template, with a single view and label in the view (label is optional)
2. In the main view controller's `viewDidLoad` method, call the following snippet below which calls into drawViewHierarchyInRect:afterScreenUpdates:
3. Perform a four finger swipe (slowly) on the app to move to another app

Snippet:

    dispatch_async(dispatch_get_main_queue(), ^{
        CGRect rect = self.view.bounds;
        UIGraphicsBeginImageContextWithOptions(rect.size, YES, 0.0f);
        [self.view drawViewHierarchyInRect:rect afterScreenUpdates:YES];
        UIImage *snapshotImage = UIGraphicsGetImageFromCurrentImageContext();
        UIGraphicsEndImageContext();
        
        //Don't need to actually do anything with our image to reproduce the bug,
        //so we'll just log it to the console. After this code has run, four finger
        //gestures (to swipe between apps, or background the current app) will show
        //a black frame on iOS 10
        NSLog(@"%@", snapshotImage);
    });

*** Comments ***
Contact info:
Twitter: @hmblebee    |    http://sound-of-silence.com/