title: IOS login screen before tab-controller view
body: <p>I am still newbie for IOS Developing, i want to create a login page by MoralViewcontroller.</p>
  
  <p><strong>AppDelegate.h</strong></p>
  
  <pre><code>@interface AppDelegate : UIResponder &lt;UIApplicationDelegate&gt;{
  
       UITabBarController *tabBarController;   }
  
  @property (nonatomic,retain) IBOutlet UITabBarController * tabBarController
  </code></pre>
  
  <p><strong>AppDelegate.m</strong></p>
  
  <pre><code>(void)applicationDidFinishLaunching:(UIApplication *)application
  {    
    // Override point for customization after app launch 
  
    [window addSubview:tabBarController. view];   
    [window makeKeyAndVisible];
    LoginViewController *loginView=[[LoginViewController alloc]initWithNibName:@"LoginViewController" bundle:nil];
  
    [tabBarController.view presentModelViewcontroller: loginView animated:YES];
  
  }
  </code></pre>
  
  <p>However, the login view cannot be shown, I think I define wrongly for tabBarController, but I don't know what wrong with it. Can anyone please advise me? I am doing IOS 5.</p>
  
  <p>Thanks alot..</p>