Вы должны установить заголовок из UIViewController. Попробуйте это:
controller.navigationItem.title=@"Application";
Infact Apple docs на UINavigationItem для свойства title указывает, что:
title
A localized string that represents the view that this controller manages.
@property(nonatomic, copy) NSString *title
Discussion
Subclasses should set the title to a human-readable string that represents the view to the user. If the receiver is a navigation controller, the default value is the top view controller’s title.
Availability
Available in iOS 2.0 and later.