NetworkingEvolution_Step5_NetworkClient.swift

import Alamofire
import SwiftyJSON

protocol NetworkClientType {
  func makeRequest<Response: JSONDecodable>(url: String,
                                            params: [String : AnyObject],
                                            callback: (Response?, ErrorType?) -> Void)
}

struct NetworkClient: NetworkClientType {
  func makeRequest<Response: JSONDecodable>(url: String,
                                            params: [String : AnyObject],
                                            callback: (Response?, ErrorType?) -> Void)
  {
    request(.POST, url, parameters: params).response { _, _, data, error in
      if let jsonData = data where error == nil {
        let json = JSON(data: jsonData)
        let response = Response(json: json)
        callback(response, nil)
      }
      else {
        callback(nil, error)
      }
    }
  }
}