how to load UINavigationController from Uiviewcontroller
@interface ContactUs : UIViewController {

    IBOutlet UIWindow *window;

    IBOutlet UINavigationController *navController;

}

@property (nonatomic,retain) IBOutlet UINavigationController *navController;

@end

and in implementation ..

// Implement viewDidLoad to do additional setup after loading the view, typically from a nib.

 -(void)viewDidLoad {

  [window addSubview:navController.view];

  [window makeKeyAndVisible];

    [super viewDidLoad];


        NSLog(@":::::::::::::::::::");

}

@interface ContactUs : UINavigationViewController {

      IBOutlet UIWindow *window;

      IBOutlet UITextView *textView;
      IBOutlet UIButton *button;

       }

   // Add properties to the all outlets //

     -(IBAction) buttonpressed: (id) sender;

@interface ContactUs : UINavigationViewController {

          IBOutlet UIWindow *window;

          // IBOutlet UINavigationController *navController; // You do not need this.

         }