Hiding a UINavigationController on start page

Hiding a UINavigationController on start page

Hi I have a navigationController that starts with a view controller in
which in viewDidLoad has:
self.navigationController.navigationBarHidden = YES;
I click a button on that page and it transitions to a second view
controller in which I put:
self.navigationController.navigationBarHidden = NO;
This works fine until I click the Back button in the navigation bar. How
do I keep the navigation bar permanently off the start page but not the
transitioned one?