title: navigationItem not showing
body: <p>I am currently writing an iOS-APP based on mostly UITableViewControllers. The hierarchy is the following:</p>
  
  <blockquote>
    <p>AppDelegate -> UINavigationController -> UITableViewController [A]
    -(didSelectRow: presentModalVC)-> UITabBarController -(contains multiple)-> UINavigationController -> UITableViewController [B]</p>
  </blockquote>
  
  <p>Now when I try to add a navigationItem in UITableViewController [B] in the viewDidLoad method like so:</p>
  
  <pre><code>self.navigationItem.rightBarButtonItem = [[UIBarButtonItem alloc] initWithBarButtonSystemItem:UIBarButtonSystemItemCompose target:self action:@selector(composeTweet:)];
  </code></pre>
  
  <p>the navigationItem does not show.</p>