Open Radar

 
Summary:

The preferred way of taking snapshot image of a view is to use UIView’s “drawViewHierarchyInRect:afterScreenUpdates:” method. This is explained in Technical Q&A QA1817 (https://developer.apple.com/library/ios/qa/qa1817/_index.html).

When making a snapshot with this method on an app that is not optimised for iPhone 6 or iPhone 6+ there is a visible flicker of the current view after calling snapshotting code. 

Steps to Reproduce:

1. Create a new single view application project
2. Disable iPhone6 and iPhone 6+ support by going to main target settings and removing launch screen file setting (deleting the LaunchScreen.xib)
3. Add the following code to ViewController.m:

- (UIImage *)snapshot:(UIView *)view
{
    UIGraphicsBeginImageContextWithOptions(view.bounds.size, YES, 0);
    [view drawViewHierarchyInRect:view.bounds afterScreenUpdates:YES];
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return image;
}

- (IBAction)takeScreenshot:(id)sender
{
    UIImage *snapshot = [self snapshot:self.view];
}

3. In the storyboard add some views (to make the effect more visible) and a single button.
4. Attach button to takeScreenshot: action in ViewController.m
5. Launch app on iPhone 6 or iPhone 6+ (or corresponding simulators).
6. Tap button to take the snapshot

Expected Results:

Nothing visible should happen because snapshot image is produced and immediately discarded

Actual Results:

Screen flickers after tapping the button.

Notes:

It seems that a similar issue was reported happening on iPad (rdar://17292507) however it is marked as fixed.