title: webViewDidFinishLoad in WKWebView
body: <p>I have to migrate from UIWebView to WKWebView and I'm having some trouble with this. It looks like that "WKWebView" has no member 'request'. Is there a way to handle this situation using the WKWebView? I simply need to get the URL loaded and then if it contains ".pdf" just show a button.</p>
  
  <pre><code>func webViewDidFinishLoad(_ webView : WKWebView) {
      UIApplication.shared.isNetworkActivityIndicatorVisible = false
  
      if (webView.request?.url!.absoluteString)!.range(of: ".pdf") != nil {
          pdfBackButton.isHidden = false
      }
      else {
      pdfBackButton.isHidden = true}
  
  }
  </code></pre>