Navigating another screen when tabbar selected when user already logged in another tab-iOS

Question

My app has four tabs that displays different information.

In my second tab view controller i have one button lets name it as button1 in that button1 action i have navigated to SignInViewController screen and in my third tab view controller is loginViewController.

Here purpose of both SignInViewController and loginViewController screen is same i.e.,user can logged into the app in both the ViewController's.

Here what i want exactly is, if I am logged in SignInViewController then whenever I tap on third TabBarItem View Controller should directly navigated to next screen of loginViewController i.e.,to that next screen i have named it as AccountViewController. I have tried below code in tabbarcontroller class but its does not working.

Please help me on this. Thanks in Advance.

- (void)tabBarController:(UITabBarController *)tabBarController didSelectViewController:(UIViewController *)viewController
{

       if (tabBarController.selectedIndex == 2){

        {

          if (![[[NSUserDefaults standardUserDefaults]objectForKey:@"SigninStatus"] isEqualToString:@"SigninSuccess"]){

                UIStoryboard *story =  [UIStoryboard storyboardWithName:@"Main" bundle:nil];
                LoginViewController *logInVc = [story instantiateViewControllerWithIdentifier:@"LoginViewController"];
                [self.navigationController pushViewController:logInVc animated:YES];
            }
            else
            {

                UIStoryboard *story =  [UIStoryboard storyboardWithName:@"Main" bundle:nil];
                AccountViewController *accountVc = [story instantiateViewControllerWithIdentifier:@"AccountViewController"];
                [self.navigationController pushViewController:accountVc animated:YES];

            }
        }
    }  
}

Answer 1

1.Is your loginViewController is embedded inside UINavigationController?

-If not than embed it inside UINavigationController

2.Create a Push Segue from loginViewController to AccountViewController e.g. segue identifier: segueLoginToAccount

3.Now when user click on 3rd tab bar item, create a check in viewDidLoad on loginViewController, to see whether user has already logged in or not:

-(void)viewDidLoad {
    [super viewDidLoad];

    if ([[[NSUserDefaults standardUserDefaults]objectForKey:@"SigninStatus"] isEqualToString:@"SigninSuccess"]) {
        //already logged in, push to Account View
        [self performSegueWithIdentifier:@"segueLoginToAccount" sender:nil];
    }//else user will stay on Login View
}

No need to use tabBarController didSelectViewController: method.