====== NavigationController ======
Add a UIViewController named RootViewController to your empty project


===== Create a NavigationController for your project =====

First step import the RootViewController.h in your AppDelegate
<code objc>
#import "RootViewController.h"
</code>

Second step initialize NavigationController with RootViewController and add it to window
<code objc>
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions
{   
    // ** initialize window **
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    // Override point for customization after application launch.
    
    // ** initialize RootViewController **
    RootViewController *rootVC = [[RootViewController alloc] initWithNibName:@"RootViewController" bundle:nil];
    
    // ** Initalize NavigationController with RootViewController **
    UINavigationController *navVC = [[UINavigationController alloc]initWithRootViewController:rootVC];

    // ** Add NavigationController **
    self.window.rootViewController = navVC;
    
    self.window.backgroundColor = [UIColor whiteColor];
    [self.window makeKeyAndVisible];
    return YES;
}
</code>