Inside the technology behind iOS 7’s parallax effect | Macworld
A good accompaniment to the earlier post about iOS 7’s computational expense is this rundown on just how parallax and perspective work on us visually. While it might seem to be a bit of a gimmick, the home screen parallax actually reinforces a key design notion in iOS 7 of depth and layers. Your wallpaper is meant to reside at the bottom of iOS 7’s world, the home screen apps float on top. When selecting an app, it zooms into that app – bringing it on top of the home screen. All of this underscores the original iOS convention that you can get home by pressing the home button, only now it locates home in a more physical space – home is at the bottom.
It also corresponds to an apparent hardware goal of Apple’s. When John Gruber saw the iPhone 4 (first retina screen and the first one where Apple fused the LCD directly to the glass) he remarked that it went from looking like pixels under glass to pixels painted on glass. I think this was Apple’s design goal and now they are taking it one step further in both the hardware and software. Your wallpaper is rendered way down there, your apps float on the top of the glass and when you open one, it renders its contents on top of it all. Very Apple idea: hardware and software all reading from the same consistent playbook.