try this inside didFinishLaunchingWithOptions method
self.window.rootViewController = self.viewController;
Question
I am testing my application on ios7 os iphone.In that am going from portrait viewcontroller to landscape viewcontroller.before going to landscape view my navigation bar height is 44 pixel.but coming from landscape view its height is reduce to landscape view navigation bar.I checked all orienation code.Please help me to solve this.
La solution
try this inside didFinishLaunchingWithOptions method
self.window.rootViewController = self.viewController;