iOS: ориентация устройства при загрузке

It seems that when my app loads, it does not know its current orientation:

UIInterfaceOrientation orientation = [[UIDevice currentDevice] orientation];
if (orientation == UIDeviceOrientationPortrait) {
    NSLog(@"portrait");// only works after a rotation, not on loading app
}

Once I rotate the device, I get a correct orientation, but when I load the app, without changing the orientation, it seems that using [[UIDevice currentDevice] orientation] doesn't know the current orientation.

Is there another way to check this when I first load my app?