I\'m investigating the use of a storyboard for launch images for my app. The app has always used a large photo for the launch image, which is also used as the background for
Apple these days encourages you to think of rotation not in terms of device orientation, but just as an animated bounds change (sometimes with a semantic hint).
We saw why with the iPhone 6 Plus — what used to be a "phone, portrait" interface becomes a sidebar interface in landscape on certain phones.
The more your view controllers assume about devices and their orientation, the harder is is to adapt to new devices that offer new ways of reusing view controllers.
Also, UIDeviceOrientation is not the same as UIInterfaceOrientation. If you use the former to make UI decisions, you'll be stymied when the device is face-up or face-down, and (IIRC) your users will be frustrated when your app doesn't respect Orientation Lock.
So what's the difference between a landscape and portrait iPad? Both are Regular x Regular in traits... But one has bounds that are taller than they are wide, and vice versa. It's totally okay to make high-level layout decisions based on aspect ratio (and use auto layout for the details).