title: How to hide share button in QLPreviewController using swift?
body: <p>I'm using the below code to use QLPreviewcontroller to show some documents in my app,</p>
  
  <pre><code>let ql = QLPreviewController()
  ql.dataSource = self
  //ql.navigationItem.rightBarButtonItems = nil
  ql.navigationItem.rightBarButtonItem = nil
  presentViewController(ql, animated: true, completion: nil)
  </code></pre>
  
  <p>I don't want the share button in the right top of QLPreviewcontroller. I'd tried setting <code>rightBarButtonItem</code> to nil, but it's not working.</p>
  
  <p>How can I hide that?</p>