Alamofire Content-Type application/json for PUT method
<p>I'm now finding solution for add <code>content-type: application/json</code> in Alamofire Content-Type application/json for PUT method. I've developed as follow, but not working correctly.</p>

<pre><code>        Alamofire.request(.PUT, Config.preferenceURL, parameters: param, headers: headers)
            .validate(contentType: ["application/json"])
            .responseJSON { response in
                let swiftyJsonVar = JSON(response.result.value!)
                print(swiftyJsonVar)
                if (swiftyJsonVar["success"]) {

                }

                JHProgressHUD.sharedHUD.hide()
        }
</code></pre>