title: How to use Moya to download file
body: <p>Usual I use <code>Alamofire</code> &amp; <code>Moya/RxSwift</code> &amp; <code>ObjectMapper</code> to analysis object
  But now add a demand. My app need download file.</p>
  
  <p>I have use </p>
  
  <pre><code>Alamofire.download(urlString, to: destination) 
  </code></pre>
  
  <p>Temporary solved the problem</p>
  
  <p>but It's not elegant.</p>
  
  <p>I want use Moya to Maintain the same network layer.</p>
  
  <p>Can you show a Download Moya"s "TargetType"</p>