func HttpRequest() {
        let url = "URLをいれてね"
        let headers: HTTPHeaders = [ 
            "Contenttype": "application/json"
        ]
        let parameters:[String: Any] = [
            "username": username,
            "password": password
        ]

        Alamofire.request(url, method: .post, parameters: parameters, encoding: JSONEncoding.default, headers: headers).responseJSON { response in
            if let result = response.result.value as? [String: Any] {
                print(result)
            }
        }

    }