title: iOS 10: Got a keyboard will show notification but keyboard was not on screen
body: <p>I have a function to handle the <code>UIKeyboardWillShow</code> notification. What happens though is that when I segue out of that specific view controller to another one and then come back, if the keyboard was still on screen before it again calls the function even though it's not on screen anymore and shows this in the console: "got a keyboard will show notification but keyboard was not on screen." However, if I hide the keyboard while still in the initial view controller and then segue and come back, the function isn't called as expected. I've tried <code>resignFirstResponder()</code> in <code>viewWillDisappear()</code> but it still happens. Any help would be appreciated!</p>