title: How to capture a full page screenshot of WKWebview?
body: <p>I can capture all content screenshot of <code>UIWebView</code> by adjust frame of <code>UIScrollView</code> of <code>UIWebView</code>. However, I can't capture all content  screenshot of <code>WKWebView</code> by the same method.</p>
  
  <p>The method I used for capture <code>UIWebView</code> as follow:</p>
  
  <ol>
  <li>backup frame and superview of <code>webview.scrollView</code></li>
  <li>create a new container view as <code>webview.scrollView</code>'s superview</li>
  <li>adjust frame of new container view and <code>webview.scrollView</code>. frame is same to <code>webview.scrollView.contentSize</code> </li>
  <li>draw by <code>renderInContext</code> or <code>drawViewHierarchyInRect</code></li>
  </ol>
  
  <p>However, this method will capture a white screenshot of <code>WKWebview</code>. It doesn't work!</p>
  
  <p>I had print all level of <code>WKWebView</code>, then I found a <code>UIView</code>(WKContentView)'s size is same to contentView, you can found this view by this level:</p>
  
  <ul>
  <li>WKWebView
  
  <ul>
  <li>WKScrollView
  
  <ul>
  <li>WKContentView(size is same to contentView)</li>
  </ul></li>
  </ul></li>
  </ul>
  
  <p>I also had try to capture by <code>WKContentView</code>, then I found only visible view could be captured.</p>
  
  <p>Anyway, Anyone could tell me how to capture a full page content screenshot of <code>WKWebView</code>?</p>