Obtain absolute rotation using CMDeviceMotion?

Question

I\'m building a simple game with Sprite Kit, the screen doesn\'t rotate but I want to know the angle the user is holding the phone for a game mechanic.

The values I

Answer 1

This is what I'm trying now. I got to it through experimentation so I cannot tell if it's correct, probably there is a better solution.

            if let attitude = motionManager.deviceMotion?.attitude? {
                 // Convert pitch and roll to [-1, 1] range
                let pitch = CGFloat(-attitude.pitch * 2 / M_PI)
                let roll = CGFloat(abs(attitude.roll) > M_PI / 2 ? (2 - abs(attitude.roll) * 2 / M_PI) * (attitude.roll > 0 ? 1 : -1) : attitude.roll * 2 / M_PI)

                // Calculate x and y
                let y = pitch
                let x = roll*(1.0-abs(pitch))
            }