title: Button item not shown in navigationBar embebed in TabBarController
body: <p>I'm working on an app where a viewController is embebed in navigationBar and this navigationBar is embebed in TabBarViewController.</p>
  
  <p>In my app I have 2 different tabs (for the moment), one tab is the "Activity view". This is a viewController with a tableView where list activities. Every cell will show the same view controller showing detail activity when it's touched.</p>
  
  <p>My problem is that not showing navigationItem with buttons. </p>
  
  <p>I'm trying the solution of: <a href="https://stackoverflow.com/questions/33696523/bar-button-item-not-shown-in-navigationbar">Bar button item not shown in navigationBar</a> , because my problem is very similar but it did not work.</p>
  
  <p>some screenshots of storyboard and app running:
  <a href="https://i.stack.imgur.com/xQPcV.png" rel="nofollow noreferrer">storyboard</a>
  <a href="https://i.stack.imgur.com/mQnUm.png" rel="nofollow noreferrer">App running without buttons</a></p>
  
  <p>I'm trying programmatically add buttons but no results:</p>
  
  <pre><code>var logoutButton: UIBarButtonItem!
  var filterButton: UIBarButtonItem!
  
  
  //MARK: - Lyfe cycle
  override func viewDidLoad() {
  super.viewDidLoad()
  
  let logoutImage = UIImage(named: "logout-24")
  let filterImage = UIImage(named: "filterOutline-24")
  
  logoutButton = UIBarButtonItem(image: logoutImage, style: .Plain, target: self, action: "logoutAction:")
  filterButton = UIBarButtonItem(image: filterImage, style: .Plain, target: self, action: "filterAction:")
  navigationItem.rightBarButtonItems = [filterButton, logoutButton]
  </code></pre>