NavigationController becomes nil after popToViewController

Answer 1

I'm not sure I've understand what you are trying to do but, when you go back to ChoicheDetailViewController i think you should do a [self.navigationController popViewController:...] instead of [self.navigationController dismissModalViewControllerAnimated:YES] because ChoicheDetailViewController got pushed on the stack in a non modal way in the first place. So with your code you are actually dismissing the whole navigationController.