Extracting message body from the push notification data structure

Question

I have a delegate class that handles push notification messages from the Amazon Web Servercies. Whenever my app receives notification from AWS, didReceivePushNotification function gets called. One of the parameters of the function contains push notification in a data structure that I'm not sure of. It looks very similar to JSON. What I would like to do is extract the message from the data structure, so that I can display it in the alert box.

This is delegate class that handles push notification from AWS :

extension PushNotificationHandler: AWSPushManagerDelegate {

  func pushManager(pushManager: AWSPushManager, didFailToRegisterWithError error: NSError) {
    print("Failed to Register for Push Notification: \(error)")
  }

  func pushManager(pushManager: AWSPushManager, didReceivePushNotification userInfo: [NSObject : AnyObject]) {

    /* userInfo.description contains push notification data */
    /* I want to extract the message here so that I can display it in alertbox */

    print("Received a Push Notification: \(userInfo.description)")

  }

} 

The push notification structure that is passed as a parameter has this format and I want to extract value of alert from it:

[
  aps: {
    alert = "xxxx have something to say";
  }
]

I tried parsing it as a JSON and having exceptions like "incorrect data format". So I'm not even sure if it is because the data is not in JSON or I'm doing it wrong.

Anyway, this is my attempt in parsing it as JSON

if let jsonData = userInfo.description.dataUsingEncoding(NSUTF8StringEncoding)
        {
            if let jsonResult: NSDictionary = try NSJSONSerialization.JSONObjectWithData(jsonData, options: NSJSONReadingOptions.MutableContainers) as? NSDictionary
            { //data not correct format
                if let aps : NSObject = jsonResult["aps"] as? NSObject
                {
                    // Do stuff
                    print("aos--" + String(aps))
                }
            }
        }