title: Get header data from a request response in swift
body: <p>I want to get X-Dem-Auth in a header request with swift to stock that in my app.</p>
  
  <p>See the response :</p>
  
  <pre><code>headers {
      "Content-Length" = 95;
          "Content-Type" = "application/json; charset=utf-8";
          Date = "Fri, 15 Apr 2016 08:01:58 GMT";
          Server = "Apache/2.4.18 (Unix)";
          "X-Dem-Auth" = null;
          "X-Powered-By" = Express;
  </code></pre>