Track device orientation when orientation is locked

Question

I need to track device orientation even though device orientation is locked to Portrait mode. What I really need is to accomplish similar behaviour to what Instagram camera view has: when you rotate device, it will rotate buttons over camera view, even when your device is locked.

I used to track orientation with UIDeviceOrientationDidChangeNotification, but that is not fired when device orientation is locked :(

Is there perhaps implementation somewhere using accelerometer and/or gyroscope? I'm suprised I couldn't find something like that.

Answer 1

Use the accelerometer to detect device orientation yourself. You can use the Core Motion framework to get the data you need. There's a sample snippet in the linked docs that shows how to get the data. Use a low-pass filter to isolate the force of gravity from relatively short-term changes due to user movement. Apple has a sample project called AccelerometerGraph that demonstrates this.