title: How to calculate the height of a WKWebView?
body: <p>I want to calculate the height of a WKWebView in my project like this, but it always no use, how can I get it?</p>
  
  <pre><code>-(void)webView:(WKWebView *)webView didFinishNavigation:(WKNavigation     *)navigation{
      [webView sizeToFit];
      _height = webView.frame.size.height ;
  }
  </code></pre>