TabbedView not displaying the Navigation bar

TabbedView not displaying the Navigation bar

iOS beginner here. I'm Using XCode 4.6.3 and doing some tutorials. I have
a question regarding a TabbedView not displaying the Navigation bar:
I set the Top Bar attribute here:
But it doesn't show here:
Below is the code in the AppDelegate:
self.navController = [[UINavigationController alloc]
initWithRootViewController:viewController1];
self.navController.navigationBar.barStyle = UIBarStyleBlack;
self.tabBarController = [[UITabBarController alloc] init];
self.tabBarController.viewControllers = @[viewController1,
viewController2];
self.window.rootViewController = self.tabBarController;
What am I doing wrong?