What's the meaning of “App must be built for iOS devices with Retina display”

Question

Apple announced that recently: \'Starting May 1, new apps and app updates submitted to the App Store must be built for iOS devices with Retina display and iPhone apps must a

Answer 1

It means that the app must be Resolution Independent (scroll down a bit), meaning that it must look good no matter what resolution it is rendered at, especially at the higher DPI (dots per inch) of the Retina displays.

You should be fine for vector graphics and, I imagine, 3D applications, but you must ensure that the final display resolution is not programmatically limited. So yes, scaling an OpenGL app should work, given that it doesn't look like crap on a high DPI device.

As for non-vector images, the Apple Developer site addresses that in "Custom Icon and Image Creation Guidelines".