如何在 Swift 4 中将 Encodable 或 Decodable 作为参数传递？

Question

我正在学习 JSONParsing。我跟着教程，我得到的是：

    guard let url = URL(string: "http://localhost/test-api/public/api/register") else { return }

    var request  = URLRequest(url: url)

    request.httpMethod = "POST"

    let newUser = User.init(name: self.collectionTF[0].text, email: self.collectionTF[1].text, password: self.collectionTF[2].text)

    do {

        let jsonBody = try JSONEncoder().encode(newUser)

        request.httpBody = jsonBody

    } catch { }

    URLSession.shared.dataTask(with: request) { (data, response, error) in

        guard let data = data else { return }

        do {

            let json = try JSONSerialization.jsonObject(with: data) as? [String:Any]

            print(json!)

            DispatchQueue.main.async {

            if json!["status"] as! Int == 200
            {
                GeneralHelper.shared.keepLoggedIn()

                NavigationHelper.shared.moveToHome(fromVC: self)
            }

            }

        } catch { print(error.localizedDescription)}

        }.resume()

好的，这就是我为注册所做的。现在，我想创建一个 Helper，它将对 @escaping 做同样的事情，因为我们都需要解析后的 JSON 作为回报。

所以，我将endPoint 作为字符串传递，然后尝试传递这个新用户，它是Encodable，将来也可以是Decodable，但它会引发错误Cannot invoke 'encode' with an argument list of type '(Codable)'。有人可以帮忙吗？而且，在JSONParsing 中多次调用这个函数，这样会更好吗？

编辑：-所以，我现在使用networkRequestfunction，这就是我所做的。

 let newData = User.init(name: "Rob", email: "abc@gmail.com", password: "12345678")

ApiHelper.sharedInstance.networkRequest_Post(urlString: "register", header: nil, encodingData: newData) { (response: User, urlRes, error) in
        <#code#> }

现在，它给了我这个错误：Cannot convert value of type '(User, _, _) -> ()' to expected argument type '(_?, HTTPURLResponse?, Error?) -> ()'。有什么帮助吗？

Answer 1

我在我的项目中使用了相同的功能

希望下面的代码会有所帮助

    func networkRequest_Post<T: Decodable, Q: Encodable>(urlString: String,header:[String:String]?,encodingData: Q,completion: @escaping (T?, HTTPURLResponse?, Error?) -> ()) {

    guard let url = URL(string: urlString) else { return }
    let config = URLSessionConfiguration.default
    config.timeoutIntervalForRequest = 300.0
    config.timeoutIntervalForResource = 300.0
    if header != nil{
        config.httpAdditionalHeaders = header
    }
    let session = URLSession(configuration: config)
    var request = URLRequest(url: url)
    request.httpMethod = "POST"
    do {
        let jsonBody = try JSONEncoder().encode(encodingData)
        request.httpBody = jsonBody
    } catch {}
    let task = session.dataTask(with: request) { (data,response, err) in

        if let response = response {
            print(response)
        }
        if let err = err {
            print("Failed to fetch data:", err.localizedDescription, "Error Description\(err)")
            return
        }
        guard let data = data else { return }
        do {
            print(String(data: data, encoding: String.Encoding.utf8) as Any)
            let dataReceived = try JSONDecoder().decode(T.self, from: data)
                completion(dataReceived,response as? HTTPURLResponse,err)
        } catch let jsonErr {
            print("Failed to serialize json:", jsonErr, jsonErr.localizedDescription)
            completion( nil,response as? HTTPURLResponse,jsonErr)
        }
    }
    task.resume()
}

使用 -

         let newdata = User(name: "Abhi", email: "jhjhj@jhj.co", password: "123hguhj")
    networkRequest_Post(urlString: "YOUR_URL", header: nil, encodingData: newdata) { (RESPONSE_DATA:User?, URL_RESPONSE, ERROR) in
        // Do your network work here
    }

    struct User : Codable {
      var name: String?
      var email: String?
      var password: String?
    }

Answer 2

您可以通过以下方式使用泛型...

func requestWith<T>(method: HTTPMethod, action: String,  params: Parameters?, for type: T.Type, success: @escaping (AnyObject) -> Void, failure: @escaping (AnyObject) -> Void) where T: Codable {


//do your stuff..your logic goes here..see below example

     guard let serverData = response.data else {
           return
        }

   do {
     let decoder = JSONDecoder()
     let responseData = try decoder.decode(type, from: serverData)
       success(responseData as AnyObject)
    } catch {
      print("Error = \(error.localizedDescription)")
       failure(error.localizedDescription as AnyObject)
   }

}