I’ve just started playing with CMMotionManager on my iPhone in an OpenGL
program. I allocate CMMotionaManger and startDeviceMotionUpdates in
-viewDidLoad. In -update I check if deviceMotionActive and print the roll value.
motionManager.deviceMotion.attitude.roll
For the first few
Not sure if it's relevant but I've noticed that since iOS 7, motion-sensitive
apps ask for a calibration almost every time, where the phone has to be rolled
around until a circle completes. It never used to do that, or only in very
specific cases, or when the user clicked a calibration button.
