UITabbar disappear when pushing

i'm having trouble with a navigation Controller, when i'm pushing my view controller to an xib a see a UITabbar but in mij xib where i'm pushing the view to i'm doing this to push the xib where i'm pushing to, to another file but when i use this line of code the UITabbar doesn't show up.

What i'm doing in view controller 1 i check if a JSON file contains 0,1 or 2 items when it's for example '1' item in the JSON i would like to push the view controller to a file special for the '2 item file' i'm pushing on this way:

   UIViewController *rootController = 
     [[2ViewController alloc] 
      initWithNibName:@"2ViewController" bundle:nil];
 
     navigationController = [[UINavigationController alloc]
                             initWithRootViewController:rootController];
 
     self.window = [[UIWindow alloc] initWithFrame:[[UIScreen mainScreen] bounds]];
     [self.window addSubview:navigationController.view];
     [self.window makeKeyAndVisible];
 

But when i do that the UITabbar disappear 'under' the view controller. Could somebody help me out solving this problem please?

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