title: SFSafariViewController as subview
body: <p>I would like to use the SFSafariViewController but still add a few buttons of my own below. I havn't found a way to do this.</p>
  
  <p>I tried using </p>
  
  <pre><code>let svc = SFSafariViewController(URL: testURL)
  self.containerView.addSubview(svc.view)
  </code></pre>
  
  <p>This results in a blank white screen.
  Is there a way to accomplish this with SFSafariViewController or do I have to build my own "browser" with WKWebView?</p>
  
  <p>Thanks in advance!</p>