I have a minor trouble hiding the navigationBar for my UINavigationController
I have added:
self.navigation!.navigationBar.hidden = true
Look at this site: https://developer.xamarin.com/recipes/ios/content_controls/navigation_controller/make_the_nav_bar_disappear/
This site says that "The behavior is slightly different depending on whether the Nav Bar is opaque or translucent"
I hope it is helpful.