Using Result with URLsession

URLSession+Extension.swift

public enum NetworkingError: Error {
    case unknown
    case unexpectedStatus(HTTPURLResponse)
}

extension URLSession {
    func load(_ url: URL,
        completionHandler: @escaping (Result<Data, Error>) -> Void)
        -> URLSessionDataTask {
        let task = dataTask(with: url) { data, response, error in
            if let error = error {
                completionHandler(.failure(error))
            }

            guard let httpResponse = response as? HTTPURLResponse,
                  let data = data else {
                completionHandler(.failure(NetworkingError.unknown))
                return
            }

            guard (200...299).contains(httpResponse.statusCode) else {
                completionHandler(.failure(NetworkingError.unexpectedStatus(httpResponse)))
                return
            }

            completionHandler(.success(data))
        }

        task.resume()
        return task
    }
}