Swift4 urlSession 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，我构建了 API 来处理这个问题并使用 Postman 获得良好的响应，但是当我尝试使用 Swift4 新的 urlsession JSON 解码和编码来实现这一点时，它一直失败，并且在解码响应数据时出错。 这是我使用邮递员时的 JSON 响应：

{
"error": "false",
"message": "downloaded",
"UserInfo": {
"id": 5,
"email": "[e-mail]",
"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?

}

我的函数

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: "[e-mail]", 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

我终于想通了，谢谢，。 我只想提到此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]

它应该是

let UserInfo: UserData?

没有方括号。 更重要的一点是，始终尝试捕获解码错误，并且通过实现 }catch let JsonErr { 来捕获它，它会准确地告诉您解码不起作用的原因。

就我而言：

下载..下载后有问题 typeMismatch(Swift.Array， Swift.DecodingError.Context(codingPath： [h2h.用户。(_E33F61CC43E102744E4EF1B7E9D7EDDE中的编码键)。用户信息]， debugDescription："预期解码数组，但发现 字典代替"，底层错误：无))

并确保使服务器 API 接受 JSON 格式的应用程序/json 和 解码您发送的内容，以便接收所需的内容; 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 得到响应时，然后写

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

Answer 3

1. 列表项

   这将起作用，您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: "[e-mail]", 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()
   }
   
   }