title: Set useragent in WKWebview
body: <p>How do I set a custom useragent string in a WKWebView? I'm trying to embed the version of my app so that my server-side can see what features are available. I found the following method:</p>
  
  <pre><code>let userAgent = "MyApp/1.33.7"
  request.setValue(userAgent, forHTTPHeaderField: "User-Agent")
  
  NSURLConnection.sendAsynchronousRequest(request, queue: NSOperationQueue.mainQueue()) {(response, data, error) in
      let content = NSString(data: data, encoding: NSUTF8StringEncoding)
      self.web!.loadHTMLString(content!, baseURL: url)
  }
  self.web!.loadRequest(request);
  </code></pre>
  
  <p>But this means the useragent is only set for that single request. The first other request (e.g. a forward), will mean the useragent is reset to default again. How can I more permanently configure the wkwebview to use my custom useragent string?</p>