title: Swift viewWillTransitionToSize Not Called With Split Screen
body: <p>I am implementing the split screen feature for the iPad Air 2 and iPad Mini 4. I'm trying to detect when the size of the split screen changes. When running as the primary app, either the <code>viewWillTransitionToSize</code> or <code>willTransitionToTraitCollection</code> will be executed. If my app is running as the secondary app, the <code>viewWillTransitionToSize</code> function is called when opening the secondary app or while in landscape mode, changing from 1/4 to 1/2 of the screen. When I change the secondary app from using 1/2 to 1/4 of the screen, no functions are called to help indicate that change. Is there supposed to be a function called? </p>