It seems in iOS 6, a drop shadow is automatically added to the navigation bar even when you set a custom background image. I\'m pretty sure this wasn\'t the case with iOS 5
Setting the shadowImage to a null image does work, however, the way the solution is presented results in adding a property if the OS is earlier than iOS 6.
A better way to do something that is dependent on the existence of a property or method is:
if ([self.navigationController.navigationBar
respondsToSelector:@selector(shadowImage)]) {
self.navigationController.navigationBar.shadowImage = [[[UIImage alloc] init] autorelease];
}