medium-codable-urlsession.swift

extension URLSession {
  func send<T: Decodable>(_ request: URLRequest,
                         completion: @escaping ((Result<T, Error>) -> Void)) {
    let task = dataTask(with: request) { (data, response, error) in
      if let data = data {
        do {
          let decoded = try JSONDecoder().decode(T.self, from: data)
          completion(.success(decoded))
        }
        catch let error {
          completion(.failure(error)) // decoding error
        }
      }
      else if let error = error {
        completion(.failure(error)) // data task error
      }
      else {
        completion(.failure(NSError())) // unknown error
      }
    }
    task.resume()
  }
}

// Usage example
let urlSession = URLSession(configuration: .default)
urlSession.send(request, completion: { (result: <Author, Error>) in
  // consume result
})