How to set root view controller in storyboard animated with navigation controller programmatically

will be helpful for those in need I finally found a way. I probably found the error. What i have done is cutting the branch on which i am sitting. I was releasing the view controller which i am currently in:) When viewdidDisappear called, there is no such view controller. Because i throw away it to space already.Below is my working steps. I hope it will be useful to someone. But i cant stand thinking of apple may reject my app. I wish finding a suitable way.
This is my working ultimate way of using split view controller and navigation controller as window root view controller alternately.

AppDelegate.h
@property (assign,nonatomic) UINavigationController * NC;
@property (assign,nonatomic) UISplitViewController *SVC;

AppDelegate.m
//Creating my main screen controller
//Creating my navigation controller with my view controller instance. Then
self.NC= my_navigation_controller;
self.window.rootViewController= self.NC;

 MyMainScreen.m
 -(void) OpenSplit()
 {
      //Creating my master view controller of SVC
      //Creating my detail view controller of SVC
      //Creating my SVC;
      AppDelegate * app_delegate= [[UIApplication sharedApplication] delegate];
      app_delegate.SVC= newly created my SVC;
      app_delegate.window.rootViewController= app_delegate.SVC;          
 }

MyDetailView.m
- (void) viewDidLoad()
{
    ...
    AppDelegate * app_delegate= [[UIApplication sharedApplication] delegate];
    app_delegate.NC= nil;  //i dont need it now. i am releasing. Releasing Navigation Controller release as well child controllers. I learned with testing.
}   

MyDetailView.m
-(void) closeSplitView
{
     //Creating navigation controller with my main screen view controller
     AppDelegate * app_delegate= [[UIApplication sharedApplication] delegate];
     app_delegate.NC= newly_created_NC;
     app_delegate.window.rootViewController= appdelegate.NC;
} 

 MyMainScreen.m
 -(void) viewDidLoad
 {
    AppDelegate * app_delegate= [[UIApplication sharedApplication] delegate];
    app_delegate.SVC= nil; //I am releasing it because i am working with NC now.
 }

should help you out Yes, you have to insert you called viewController to NavigationController, but if you wont to use modal flow - to close presentedViewController just call:

[self dismissViewControllerAnimated:YES completion:^{

}];

- (void)viewDidAppear:(BOOL)animated
{
    [super viewDidAppear:animated];

    UIViewController *c = [[UIViewController alloc] init];
    c.view.backgroundColor = [UIColor redColor];

    [self presentViewController:c animated:YES completion:^{
        [self dismissViewControllerAnimated:YES completion:^{

        }];
    }];
}

I think the issue was by ths following , If you are not using a storyboard then you shouldn't attempt to create your sign-in view controller from a storyboard. Change the code to create the view controller directly:

func SignIn(sender: UIButton!) {
    print("I'm, here")
    let controller = signInController()
    self.navigationController?.pushViewController(controller, animated: true)
}

will be helpful for those in need You need to initialize the window programmatically.
Try adding the following to the beginning of your didFinishLaunchingWithOptions method in Appdelegate

self.window = UIWindow()

UIApplication.shared.windows.first?.rootViewController = rootVC

window?.rootViewController = rootVC