Changing root view controller in the background

I have the following view controllers stack.

First, my app will show an app tour page. (Say TourViewController - super class is UIViewController). Added this controller in AppDelegate as rootviewcontroller.

self.window.rootViewController = tourViewController;

Then from the tour page, if the user taps on "Signin" button, I'm presenting the second view controller (Say LoginViewController - super class is UIViewController).

UINavigationController *loginNavigationController = [[UINavigationController alloc] initWithRootViewController:self.loginViewController];
[self presentViewController:loginNavigationController animated:YES completion:nil];

After a successful login, I need to resign the second view controller (LoginViewController) and want to show a tab bar based view for further needs.

I tried this code inside the login success method.

[self dismissViewControllerAnimated:YES completion:^{

        TabBarViewController *tabController = [[TabBarViewController alloc] init];

        [self presentViewController:tabController animated:NO completion:nil];

        AppDelegate *applicationDelegate = [[UIApplication sharedApplication] delegate];
        applicationDelegate.window.rootViewController = tabController;

    }];

Problems:

When I'm in the LoginViewController, I have two view controllers in my stack. So even I resign the LoginViewController, the another one (TourViewController) remains in the screen.
If I tried the above code, tab bat controller was successfully added as root view controller. But, when the LoginViewController resigns, the background was filled by TourViewController

What I need is, When I resign the LoginViewController, the background view should be tab bar controller instead of TourViewController.

Help needed!!

Solution

u can change the root view controller in AppDelegate not in the success method of the loginNavigationController better u can do this way

in AppDelegate.h

 #import <UIKit/UIKit.h>
 #import "TabControllerViewController.h"

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window;

- (void)showTabController;  //add this method call from on success method of log in completion 
@end

in AppDelegate.m

- (void)showTabController;
 {
   TabControllerViewController *tabController =    [[TabControllerViewController alloc]  initWithNibName:@"TabControllerViewController" bundle:nil];
  self.window.rootViewController = tabController;
 [self.window makeKeyAndVisible];
}

and in loginNavigationController.m

[self dismissViewControllerAnimated:YES completion:^{

    //TabBarViewController *tabController = [[TabBarViewController alloc] init];

  //  [self presentViewController:tabController animated:NO completion:nil]; //no nee to present 

    AppDelegate *applicationDelegate = [[UIApplication sharedApplication] delegate];
     [applicationDelegate showTabController]; //there is no need to create a tab bar in loginview controller, create it in root view controller 
    //applicationDelegate.window.rootViewController = tabController;

}];

NOTE: above is not tested just try it once

Edit 1

one way u can do it but with different animation, form this answer u can change to second window by doing some animation for example

in in AppDelegate.h

#import <UIKit/UIKit.h>
#import "TabViewController.h"
#import "LoginViewController.h"

@interface AppDelegate : UIResponder <UIApplicationDelegate>

@property (strong, nonatomic) UIWindow *window; //holds initial window, holds tour and login controller
@property (strong, nonatomic) UIWindow *tabWindow; //holds only tab controller 
//..other code below is my test 
@property (strong, nonatomic) TabViewController *tabViewController;
@property (strong, nonatomic) LoginViewController *loginController;
- (void)showTabController;
@end

in AppDelegate.m

- (BOOL)application:(UIApplication *)application didFinishLaunchingWithOptions:(NSDictionary *)launchOptions 
{
   _tabWindow = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];
   _window    = [[UIWindow alloc]initWithFrame:[UIScreen mainScreen].bounds];

   // Override point for customization after application launch.
   _loginController = [[LoginViewController alloc]initWithNibName:@"LoginViewController" bundle:nil];
   _tabViewController = [[TabViewController alloc] initWithNibName:@"TabViewController" bundle:nil];

    self.window.rootViewController = _loginController; //for test for your case it contains tour view controller  
    [self.window makeKeyAndVisible];
    return YES;
 }

 - (void)showTabController;
 {
    [UIView transitionWithView:self.window duration:0.5 options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
    self.window.rootViewController = _tabViewController;
    } completion:^(BOOL finished) {
      // [_tabWindow makeKeyAndVisible];
    }];
 }