iOS initial log in view before navigational Controller - ios

Question

I have been playing around with this for a couple of days and I cannot figure this out.
-> Basically I want to implement a simple login view that has a button when clicked, goes to go to the navigation controller ( in my case is "viewController" with buttons that link to mini math games which are other views).
-> Login screen should be displayed first, than navigation controller's root view when a button is clicked on the login screen
-> I have tried to declare the navigation controller when I click the button of the login screen but that seems to not work
-> Is it safe to say that a navigation controller can only be initialized in the apple delegate?
Currently I have this in my apple delegate declaring and setting my navigational controller:
- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions: (NSDictionary *)launchOptions
{
self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
// Override point for customization after application launch.
self.viewController = [[ViewController alloc] initWithNibName:#"ViewController" bundle:nil];
UINavigationController *navigationViewController = [[UINavigationController alloc] initWithRootViewController:self.viewController]; // self.viewController is the main screen
self.window.rootViewController = navigationViewController; // set root to navigationViewController
[self.window makeKeyAndVisible];
return YES;
}
Any ideas will be appreciated. Thank you for your time !

Answer 1

Your code in the app delegate looks ok. NavigationController does not need to be declared in the AppDelegate. In your case, it is definitely ok to declare it upon login button pressed.
Try this at the login event:
UIViewController *nextVC = [[UIViewController alloc] init];
UINavigationController *navController = [[UINavigationController alloc] initWithRootViewController:nextVC];
[self presentViewController:navController animated:YES completion:^{
}];

Answer 2

What I would do would be set the loginViewController as the rootViewController of the navigation. And after check if login was done successfully, you could implement [self performSegueWithIdentifier:#"identifier"] setting the game viewController as destination. (Using Storyboard would make your life much easier). Well, that's my opinion :)