The Core iOS Developer’s Cookbook, Fifth Edition

Recipe: Retrieving and Using Device Attitude

Imagine an iPad sitting on a desk. There’s an image displayed on the iPad, which you can bend over and look at. Now imagine rotating that iPad as it lays flat on the desk, but as the iPad moves, the image appears to stay fixed in place, retaining the same alignment with the world around it. Regardless of how you spin the iPad, the image doesn’t “move” with the device as the image view updates to balance the physical movement. That’s how Recipe 14-6 works, taking advantage of a device’s onboard gyroscope—a necessary requirement to make this recipe work.

The image adjusts however you hold the device. In addition to that flat manipulation, you can pick up the device and orient it in space. If you flip ...