title: UIActivityIndicator view on navigation left bar button item doesn't show for iOS 13.0 device?
body: <p>UIActivityIndicator view on navigation left bar button item doesn't show for iOS 13.0 device: 
  Here is the code:</p>
  
  <pre><code>let activityIndicator = UIActivityIndicatorView(frame: CGRect(x: 0, y: 0, width: 20, height: 20))
  activityIndicator.tintColor = UIColor.white
  activityIndicator.startAnimating()
  let barButton = UIBarButtonItem(customView: activityIndicator)
  self.navigationItem.setLeftBarButton(barButton, animated: true)
  </code></pre>
  
  <p>Please advise.
  Thanks</p>