title: How to close SFSafariViewController automatically when reaching a certain page
body: <p>I want to close SFSafariViewController automatically upon reaching the "thank you" page of the Dropbox site after the user uploads something; it needs to automatically dismiss. How can I do that? </p>
  
  <p>Here is what I have so far:</p>
  
  <pre><code>@IBAction func Singles5(_ sender: Any) {
      let safariVC = SFSafariViewController(url: NSURL(string: "https://www.dropbox/Upload")! as URL)
      self.present(safariVC, animated: true, completion: nil)
      safariVC.delegate = self
  }
  </code></pre>