Get device orientation using Accelerometer

orientation.m

    CMMotionManager *_motionManager = [[CMMotionManager alloc] init];
    _motionManager.accelerometerUpdateInterval = 0.1;
    __block UIDeviceOrientation orientationLast = UIDeviceOrientationPortrait;
    [_motionManager startAccelerometerUpdatesToQueue:[NSOperationQueue mainQueue] withHandler:^(CMAccelerometerData *accelerometerData, NSError *error) {
        UIDeviceOrientation orientationNew;
        if (accelerometerData.acceleration.x >= 0.75) {
            orientationNew = UIDeviceOrientationLandscapeRight;
        }
        else if (accelerometerData.acceleration.x <= -0.75) {
            orientationNew = UIDeviceOrientationLandscapeLeft;
        }
        else if (accelerometerData.acceleration.y <= -0.75) {
            orientationNew = UIDeviceOrientationPortrait;
        }
        else if (accelerometerData.acceleration.y >= 0.75) {
            orientationNew = UIDeviceOrientationPortraitUpsideDown;
        }
        else {
            // Consider same as last time
            return;
        }
        
        if (orientationNew == orientationLast)
            return;
        
        orientationLast = orientationNew;
    }];