Back button control press is delayed

The bug

If you press the back button control, the button only activates after a delay.
This is because any press below a certain point is interrupted by the iOS Control Center and only happens if the controls are at the bottom of the screen.
See the attached screenshot for an explanation.
This only affects Apple users in iOS 11.0 or later.

Possible fix

- (UIRectEdge)preferredScreenEdgesDeferringSystemGesture {
    return UIRectEdgeAll;
}