Swift4 url​​Session Decodable 中的 POST 方法不起作用（这里出了什么问题？）

Question

我正在尝试发布 2 个参数（电子邮件：和密码）以从服务器获取包含详细用户信息的响应，我构建 API 来处理此问题并使用 Postman 获得良好响应，但是当我尝试使用Swift4 新的 urlsession JSON 解码和编码，它一直失败，我在解码响应数据时出错。 这是我在使用 Postman 时的 JSON 响应：

{
    "error": "false",
    "message": "downloaded",
    "UserInfo": {
        "id": 5,
        "email": "abc@hotmail.com",
        "lastname": "Bence",
        "name": "Mark",
        "phone": "1234567",
        "add1": "333",
        "add2": "444",
        "city": "ott",
        "postalcode": "tttttt"
    }
}

我的结构文件：

import UIKit
struct loginPost: Encodable {
    let email: String
    let password: String
}

struct User: Decodable {
    let error: String?
    let message: String?
    let UserInfo: [UserData]

    }

struct UserData: Codable {
    let  id: Int?
    let email: String?
    let lastname: String?
    let name: String?
    let phone: String?
    let add1: String?
    let add2: String?
    let city: String
    let postalcode: String?


}

我的功能

func downloadJson() {

     let url = URL(string: http://192.168.0.10/api/login_hashed.php)
    guard let downloadURL = url else { return }
    //POST Req


    var request = URLRequest(url: downloadURL)
    request.httpMethod = "POST"
    request.addValue("application/json", forHTTPHeaderField: "Content-Type")
    request.addValue("application/json", forHTTPHeaderField: "Accept")
    let newpost = loginPost(email: "abc@hotmail.com", password: "123456")

    do {
        let jsonBody = try JSONEncoder().encode(newpost)

        request.httpBody = jsonBody
        print(jsonBody)
    }catch{
        print("some error")
    }


    URLSession.shared.dataTask(with: request) { data, urlResponse, error in
        guard let data = data, error == nil, urlResponse != nil else {
            print("something is wrong with url")
            return
        }

        print("downloaded..")
        do
        {
            let decoder = JSONDecoder()
            let downloaduser = try decoder.decode(User.self, from: data)
            self.logmessage = downloaduser.message!

            print(self.logmessage)


            DispatchQueue.main.async {

               // self.tableView.reloadData()
            }
        } catch {
            print("something wrong with decode")

        }
        }.resume() 
}

Answer 1

终于弄明白了，谢谢。 我只想提一下这个错误的原因并分享我的经验。 主要原因是您发送 JSON 和接收传入响应的方式。您应该确切地知道数据的外观，以便以可接受的方式创建您的结构。 我的返回数据只是简单的 2 行文本和文本数组，我的结构是：

import UIKit
struct loginPost: Encodable {
    let email: String
    let password: String
}

struct User: Decodable {
    let error: String?
    let message: String?
    let UserInfo: [UserData]

    }

struct UserData: Codable {
    let  id: Int?
    let email: String?
    let lastname: String?
    let name: String?
    let phone: String?
    let add1: String?
    let add2: String?
    let city: String
    let postalcode: String?


}

我在第 18 行的错误

  let UserInfo: [UserData]

应该是

let UserInfo: UserData?

没有方括号。 更重要的一点是，始终尝试通过实现 }catch let JsonErr { 来捕获解码错误，它会告诉你解码不工作的确切原因。

就我而言：

已下载.. 下载后出现问题 typeMismatch(Swift.Array, Swift.DecodingError.Context(codingPath: [h2h.User.(_E33F61CC43E102744E4EF1B7E9D7EDDE 中的 CodingKeys).UserInfo], debugDescription: "预期解码 Array 但发现了一个 字典代替。”，基础错误：无））

并确保您的服务器 API 接受 JSON 格式的 application/json 和 解码您发送的内容以接收您要查找的内容； php代码服务API

$UserData = json_decode(file_get_contents("php://input"), true);

Answer 2

解码 json 的最简单方法。

必须尝试

struct Welcome: Codable {
    let error, message: String?
    let userInfo: UserInfo?

    enum CodingKeys: String, CodingKey {
        case error, message
        case userInfo = "UserInfo"
    }
}

// MARK: - UserInfo
struct UserInfo: Codable {
    let id: Int?
    let email, lastname, name, phone: String?
    let add1, add2, city, postalcode: String?
}

之后在你的代码中，当你从 api 得到响应然后写

  let decoder = JSONDecoder()
  let obj = try! decoder.decode(Welcome.self, from: jsonData!)
  Print(obj)

Answer 3

1. 列表项

   这会起作用你创建的模型是错误的吗

   struct loginPost: Encodable {
       let email: String
       let password: String
   }
   
   struct Users:Codable {
       var error:String?
       var message:String?
       var UserInfo:UserDetails?
   }
   struct UserDetails:Codable {
       let  id: Int?
       let email: String?
       let lastname: String?
       let name: String?
       let phone: String?
       let add1: String?
       let add2: String?
       let city: String
       let postalcode: String?
   
   }
   
   
   class ViewController: UIViewController {
   
       override func viewDidLoad() {
           super.viewDidLoad()
        downloadJson()
   
       }
   
       func downloadJson() {
   
           let url = URL(string: "http://192.168.0.10/api/login_hashed.php")
           guard let downloadURL = url else { return }
           //POST Req
   
   
           var request = URLRequest(url: downloadURL)
           request.httpMethod = "POST"
           request.addValue("application/json", forHTTPHeaderField: "Content-Type")
           request.addValue("application/json", forHTTPHeaderField: "Accept")
           let newpost = loginPost(email: "abc@hotmail.com", password: "123456")
   
           do {
               let jsonBody = try JSONEncoder().encode(newpost)
   
               request.httpBody = jsonBody
               print(jsonBody)
           }catch{
               print("some error")
           }
   
           URLSession.shared.dataTask(with: request) { data, urlResponse, error in
               guard let data = data, error == nil, urlResponse != nil else {
                   print("something is wrong with url")
                   return
               }
   
               print("downloaded..")
               do
               {
                   let decoder = JSONDecoder()
                   let downloaduser = try decoder.decode(Users.self, from: data)
   
   //                self.logmessage = downloaduser.message!
   
   //                print(self.logmessage)
   
   
                   DispatchQueue.main.async {
   
                       // self.tableView.reloadData()
                   }
               } catch {
                   print("something wrong with decode")
   
               }
               }.resume()
       }
   
   
   }