Delay of button's highlighted state

Question

I have the issue in two completely different situations, which makes it really weird.

1. Situation: A UIButton in as a subView of another UIView.
2. Situation:

Answer 1

This can happen if the buttons are placed close to the bottom edge of the display. There's a conflict with the system edge gesture to present Control Center (or App Switcher on iPhone X and iPad). It delays touches for your buttons until it's determined the user isn't performing a system gesture.

If you would like, you can tell the system to give precedence to your gestures over the system gestures.

override func preferredScreenEdgesDeferringSystemGestures() -> UIRectEdge {
    return .bottom
}

Do note however that this will require the user swipe twice to activate the system gesture.