title: performSegueWithIdentifier not firing
body: <p>I have a view controller with a button that launches the twitter login page via <code>STTwitter</code>. The <code>shouldPerformSegueWithIdentifier</code>function return <code>NO</code> or <code>YES</code> depending on the isDoneTwitterLogin iVar. </p>
  
  <p>In the function <code>- (BOOL)application:(UIApplication *)application openURL:(NSURL *)url sourceApplication:(NSString *)sourceApplication annotation:(id)annotation</code>, 
  I have the following code:</p>
  
  <pre><code>LoginViewController *loginViewController = [[UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]] instantiateViewControllerWithIdentifier:@"Twitter Login"];
  [loginViewController doneTwitterLogin:YES];
  [loginViewController.navigationController performSegueWithIdentifier:@"User Info" sender:viewController];
  </code></pre>
  
  <p>The last line doesn't do anything. Neither does <code>shouldPerformSegueWithIdentifier</code> get fired. </p>
  
  <p>Anything I'm doing wrong? 
  There is a segue in my storyboard from <code>LoginViewController</code> named "User Info". </p>
  
  <p>UPDATE 1: The <code>LoginViewController</code> scene is embedded in a <code>UINavigationController</code>.
  The segue "User Info" is connected to a <code>UIButton</code> in the <code>LoginViewController</code>scene. This is the new code I tried:</p>
  
  <pre><code>LoginViewController *loginViewController = [[UIStoryboard storyboardWithName:@"Main" bundle:[NSBundle mainBundle]] instantiateViewControllerWithIdentifier:@"Twitter Login"];
  [loginViewController doneTwitterLogin:YES];
  UINavigationController *navigationController = [[UINavigationController alloc] initWithRootViewController:loginViewController];
  NSLog(@"%@", loginViewController.navigationController);
  [loginViewController.navigationController performSegueWithIdentifier:@"User Info" sender:loginViewController];
  </code></pre>
  
  <p>The previous code was returning a <code>(null)</code> navigation controller. The above code returns a valid <code>UINavigationController</code> object.</p>
  
  <p>UPDATE 2: The above code generated an error message saying that the instance of UINavigationController didn't have a segue named "User Info". I have changed the line to the one below:</p>
  
  <p><code>[loginViewController performSegueWithIdentifier:@"User Info" sender:loginViewController];</code></p>
  
  <p>But this doesn't do anything either.</p>