如何在Swift 4中将Encodable或Decodable作为参数传递? [英] How to pass Encodable or Decodable as parameter in Swift 4?

问题描述

我正在学习JSONParsing.我按照教程学习，得到的是这样:

I am learning JSONParsing. I followed tutorials and what I got is this:

    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，因为我们所有人都需要解析的JSON作为回报.

Ok, this is what I have done for register. Now, I want to create a Helper, which will do the same thing with @escaping as I we all need the parsed JSON in return.

因此，我将endPoint作为String传递，然后尝试传递此newUser(它是Encodable)，将来也可以是Decodable，但是会引发错误Cannot invoke 'encode' with an argument list of type '(Codable)'.谁能帮忙吗?而且，通过多次调用JSONParsing的此函数，这种方法是否更好?

So, I am passing the endPoint as String and then trying to pass this newUser which is a Encodable, it can be a Decodable as well in future, but it throws an error Cannot invoke 'encode' with an argument list of type '(Codable)'. Can anyone please help? And, is it better this way, by calling this function multiple times when it comes to JSONParsing?

-因此，我现在正在使用networkRequestfunction，这是我所做的.

- So, I am now using the networkRequestfunction and here is what I have done.

 let newData = User.init(name: "Rob", email: "[e-mail]", 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?) -> ()'.有帮助吗?

Now, it gives me this error: Cannot convert value of type '(User, _, _) -> ()' to expected argument type '(_?, HTTPURLResponse?, Error?) -> ()'. Any help?

推荐答案

我在项目中使用了相同的功能

I have used the same functionality in my project

希望下面的代码会有所帮助

Hope the below code will help

    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: "[e-mail]", 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?
    }

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