I have a minor trouble hiding the navigationBar for my UINavigationController
I have added:
self.navigation!.navigationBar.hidden = true
I know the question has already been answered but I was having the same issue when hiding a navigation bar then using a UIScrollView in the view.
UIScrollView
I fixed it programmatically using:
self.edgesForExtendedLayout = UIRectEdgeNone;
Or in interface builder by deselecting all of these: