In my app I would like to show a login screen - which will be displayed when the app starts and when the app becomes active. For reference, I am using storyboards, ARC and it is a tabbed bar application.

First off, I have this method which returns the topViewController.

- (UIViewController *)topViewController:(UIViewController *)rootViewController
{
    if (rootViewController.presentedViewController == nil) {
        return rootViewController;
    }

    if ([rootViewController.presentedViewController isMemberOfClass:[UINavigationController class]]) {
        UINavigationController *navigationController = (UINavigationController *)rootViewController.presentedViewController;
        UIViewController *lastViewController = [[navigationController viewControllers] lastObject];
        return [self topViewController:lastViewController];
    }

    UIViewController *presentedViewController = (UIViewController *)rootViewController.presentedViewController;
    return [self topViewController:presentedViewController];
}

And I call this method here:

- (void)applicationDidBecomeActive:(UIApplication *)application
{
    if ( ... ) { // if the user needs to login
        PasswordViewController *passwordView = [[PasswordViewController alloc] init];
        UIViewController *myView = [self topViewController:self.window.rootViewController];
        [myView presentModalViewController:passwordView animated:NO];
    }
}

To an extent this does work - I can call a method in viewDidAppear which shows an alert view to allow the user to log in. However, this is undesirable and I would like to have a login text box and other ui elements. If I do not call my login method, nothing happens and the screen stays black, even though I have put a label and other elements on the view.

Does anyone know a way to resolve this? My passcode view is embedded in a Navigation Controller, but is detached from the main storyboard.