title: titleView image appears and disappears immediately
body: <p>I'm trying to add my image on UINavigationItem using this code:</p>
  
  <pre><code>override func viewDidLoad() {
          super.viewDidLoad()
  
          self.navItemTop.titleView?.contentMode = UIViewContentMode.scaleToFill
  
          self.navItemTop.titleView? = ViewController4.navigationImage! //my image, its correct for sure
  
          self.navigationController?.navigationBar.barTintColor = UIColor.white
  
      }
  </code></pre>
  
  <p>When i go to another UIViewController and then go back, image appears and disappears a second later. I've tried to put this piece of code in viewWillAppear() method, but result is the same.
  How can i fix this? </p>