Orientation information isn’t very consistent, and there are several approaches. If in a view controller, you can use the interfaceOrientation property. From other places you can call:
[[UIDevice currentDevice] orientation]
Alternatively, you can request to receive orientation change notifications:
[[UIDevice currentDevice] beginGeneratingDeviceOrientationNotifications];
[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(orientationChanged:) name:UIDeviceOrientationDidChangeNotification object:nil];
Some people also like to check the status bar orientation:
[UIApplication sharedApplication].statusBarOrientation