iOS - Transition between different Storyboard view controllers

Question

I have divided my project into two storyboards:

• Main.storyboard - For authenticated user. Also this is the default storyboard.

• Login.storyboard - For non-authenticated user.

App delegate file:

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    if(user is authenticated)
    {
        [self presentLoginScreen:YES];
        return YES;
    }

Login Screen in app delegate file:

-(void)presentLoginScreen:(BOOL)animated{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Login" bundle:[NSBundle mainBundle]];
    UIViewController *vc =[storyboard instantiateInitialViewController];
    self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
    self.window.rootViewController = vc;
}

On logout, login Screen is presented. I defined this in app delegate file:

-(void)logOut{
   //clear data

    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Login" bundle:[NSBundle mainBundle]];
    UIViewController *vc =[storyboard instantiateInitialViewController];
    self.window.rootViewController = vc;
    //Show login Screen
    [self presentLoginScreen:NO];
}

From viewcontroller of MainStoryBoard(letsay mainstoryboardVc.m), logOut is called as:

-(void)didTouchLogOut{
    NSLog(@"GoodBye");
    AppDelegate *appDelegateTemp = [[UIApplication sharedApplication]delegate];
    [appDelegateTemp logOut];
}

This is causing a lot of issue:

• Firstly, when I log out, and move to login screen, I can still see mainstoryboardVc.m in the background which looks very clumsy.

• I log out, re-log in and again trying to log out, I see following message:

Presenting view controllers on detached view controllers is discouraged

and login screen is not presented.

I tried many answers on the web on view controller presentations between two storyboards without keeping history, nothing seems to work...

Answer 1

To swap out UIViewControllers there are a few other methods that need to be called when transitioning the root view controller:

Objective-c:

- (void)setRootViewController:(UIViewController *) newRootViewController {

    UIViewController* currentViewController = self.window.rootViewController;
    if (newRootViewController != currentViewController) {
        [currentViewController willMoveToParentViewController:nil];
        [currentViewController.view removeFromSuperview];
        [currentViewController removeFromParentViewController];
        self.window.rootViewController = newRootViewController;
    }
}

Swift:

func setRootViewController(newRootViewController: UIViewController) {
    if let currentViewController = self.window?.rootViewController {
        if currentViewController != newRootViewController {
            currentViewController.willMoveToParentViewController(nil)
            currentViewController.view.removeFromSuperview()
            currentViewController.removeFromParentViewController()
            self.window?.rootViewController = currentViewController
        }
    }
}

Answer 2

Two UIViewController objects are duplicated because you set self.window.rootViewController for both of them. Try that;

Login

-(void)presentLoginScreen:(BOOL)animated{
    UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Login" bundle:[NSBundle mainBundle]];
    UIViewController *vc =[storyboard instantiateInitialViewController];
    self.window.rootViewController = vc;
    [self.window makeKeyAndVisible];
}

Logout

-(void)logOut{
   UIStoryboard *storyboard = [UIStoryboard storyboardWithName:@"Login" bundle:[NSBundle mainBundle]];
   UIViewController *vc =[storyboard instantiateInitialViewController];
   [self presentViewController:vc animated:YES completion:nil];
}