Failure case is not executing

[tariq235]

Alamofire.request(URL, method: Endpoints.login.method, parameters: parameters, encoding: JSONEncoding.default, headers: nil)
            .responseObject { [weak self] (response: DataResponse<User>) in
                switch response.result {
                case .success(let user):
                    cb(.success(user))
                case .failure(let error):
                    log.error(error)
                    cb(.failure(error))
                }
        }

Above code always execute success case with nil user. I need my failure case to execute whenever api fails!