SwiftyJSON休息api - 返回nil

Question

SwiftyJSON来休息api - 返回nil 这是我的第一次REST Api体验

func getGif(){

        let path = "http://yesno.wtf/api"
        let url = NSURL(string: path)
        let session = NSURLSession.sharedSession()
        let task = session.dataTaskWithURL(url!){(data: NSData?, response:NSURLResponse?, error: NSError?) -> Void in
            //print(">>> \(data)")
            let json = JSON(data: data!)
            let gif = json["answer"]["forced"]["image"].string
            print("gif: \(gif)")


        }
        task.resume()
    }

我使用http://yesno.wtf/api