title: navigationItem button not showing
body: <p>I have a <code>UINavigationItem</code> i am trying to show a <code>UIBarButtonItem</code>. </p>
  
  <p>Now the problem is i added them correctly, they're functional and working 100%. </p>
  
  <p>but they're not showing on the  <code>UINavigationBar</code>. </p>
  
  <p>Now for the flow I am doing the following. </p>
  
  <p>1- I am hiding the back button, like this </p>
  
  <pre><code>self.navigationItem.setHidesBackButton(isBackHidden, animated: false)
  </code></pre>
  
  <p>2- I am adding those 2 buttons using a function dynamically at run time, when a user tap on a <code>UIButton</code>. </p>
  
  <pre><code>let rightBarItem = UIBarButtonItem(title: "Button.Done".localized, style: .plain, target: self, action: #selector(self.saveButtonTapped))
  navigationItem.rightBarButtonItem = rightBarItem     
  let leftBarItem = UIBarButtonItem(title: "Button.Cancel".localized, style: .plain, target: self, action: #selector(self.cancelButtonTapped))
  navigationItem.rightBarButtonItem?.tintColor = .red // still nothing    
  navigationItem.leftBarButtonItem = leftBarItem
  </code></pre>
  
  <p>3- I have tried to use those functions and still the same result </p>
  
  <pre><code>self.navigationItem.setLeftBarButton(UIBarButtonItem?, animated: Bool)
  self.navigationItem.setRightBarButton(UIBarButtonItem?, animated: Bool)
  </code></pre>
  
  <p><strong>Summary</strong> : </p>
  
  <p>I have tried to change the <code>tintColor</code> as they're functionally working i thought it was a color problem. </p>
  
  <p>I have tried to use them inside <code>DispatchQueue.main.async {}</code> thinking it might be a thread problem since it dynamic. </p>
  
  <p>I have  debugged and check for the items in the <code>UINavigationItem</code> and they're exist.</p>
  
  <p><strong>What is going on mainly:</strong> </p>
  
  <p>The buttons are not shown but they are working just fine when tapped on their places on the <code>UINavigationItem</code>. </p>