title: Load custom error htmlString when WKWebView loadRequest fails
body: <p>In my controller I have a call to WKWebViewInstance.loadRequest(url). If there is no internet available, I want to load an error message in the WKWebView.</p>
  
  <p>I have found that </p>
  
  <pre><code>  func webView(webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: NSError) 
  </code></pre>
  
  <p>gets called when a WKWEbView navigation fails with no internet connection. When I make the webView.loadHtmlString() call inside the above delegate method, nothing happens. </p>
  
  <p>How do I detect the absence of network connection while WKWEbView navigation request is made and load a fixed error message into web view instead?</p>
  
  <p>My delegate method code is </p>
  
  <pre><code>   func webView(webView: WKWebView, didFailProvisionalNavigation navigation: WKNavigation!, withError error: NSError) {
      webView.stopLoading()
      webView.loadHTMLString(Constants.OfflineHtmlString!,baseURL:  nil)
  }
  </code></pre>