title: AlamoFire asynchronous completionHandler for JSON request
body: <p>Having used the AlamoFire framework I've noticed that the completionHandler is run on the main thread. I'm wondering if the code below is a good practice for creating a Core Data import task within the completion handler:</p>
  <pre><code>Alamofire.request(.GET, &quot;http://myWebSite.example&quot;, parameters: parameters)
              .responseJSON(options: .MutableContainers) { (_, _, JSON, error) -&gt; Void in
                  dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), { () -&gt; Void in
                      if let err = error{
                          println(&quot;Error:\(error)&quot;)
                          return;
                      }
  
                      if let jsonArray = JSON as? [NSArray]{
                          let importer = CDImporter(incomingArray: jsonArray entity: &quot;Artist&quot;, map: artistEntityMap);
  
                      }
                  });
              }
  </code></pre>