How to trigger navigationController:willShowViewController delegate method in AppDelegate

How can I trigger the navigationController:willShowViewController delegate method for my implementation below so that all the view controllers in the navigation controller will conform to the colorWithHexString #faf6f5?

Currently, my FirstViewController will be displayed but it doesn't seem to call the delegate meth开发者_Go百科od to change the color of it's navigation bar (as well as for all other view controllers that are stacked onto the navigation controller subsequently). Note that I have already added the "UINavigationControllerDelegate" to my app delegate header file.

//In App Delegate
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    //Set First View
    FirstViewController *firstView = [[FirstViewController alloc]init];

    // pushes a nav con 
    UINavigationController *tempNavcon = [[UINavigationController alloc]initWithRootViewController:firstView];
    self.navcon = tempNavcon;

    [self.window addSubview:navcon.view];

}

- (void)navigationController:(UINavigationController *)navigationController 
  willShowViewController:(UIViewController *)viewController animated:(BOOL)animated{

    navigationController.navigationBar.tintColor = [UIColor colorWithHexString:@"#faf6f5"];

}

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is there a reason why you are trying to change the tintColor in an event method rather than when the UINavigationBar instance is created?

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Here's how you do it. (Note that UIColor doesn't accept hex values; you should use an RGB value, or check this page.

 - (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    //Initialize your view controller.
    FirstViewController * firstView = [[FirstViewController alloc] init];

    // Create an instance of a UINavigationController. Its stack contains only firstView.
    UINavigationController *navController = [[UINavigationController alloc]
                                             initWithRootViewController:firstView];

    //Here is where you set the color of the navigationBar. See my note above for using RGB.
    navController.navigationBar.tintColor = [UIColor greenColor];

    // You can now release the firstView here, navController will retain it
    [firstView release];

    // Place navigation controller's view in the window hierarchy
    [[self window] setRootViewController:navController];

    [navController release];

    [self.window makeKeyAndVisible];
    return YES;
}