无法使用与 SwiftUI 的组合从 URL 获得响应

Question

那是我的模型class

struct LoginResponse: Codable {
    let main: LoginModel
}

struct LoginModel: Codable {
    
    let success: Bool?
    let token: String?
    let message: String?
    
    static var placeholder: LoginModel {
        return LoginModel(success: nil, token: nil, message: nil)
    }
    
}

这就是我的服务。我还有一个问题，我在这里使用了两个地图，但是当尝试删除 map.data 时，dataTaskPublisher 出现错误。下面提到的错误

Instance method 'decode(type:decoder:)' requires the types 'URLSession.DataTaskPublisher.Output' (aka '(data: Data, response: URLResponse)') and 'JSONDecoder.Input' (aka 'Data') be equivalent

class LoginService {
    func doLoginTask(username: String, password: String) -> AnyPublisher<LoginModel, Error> {
        
       
        
      let networkQueue = DispatchQueue(label: "Networking",
                                           qos: .default,
                                           attributes: .concurrent)
        
        guard let url = URL(string: Constants.URLs.baseUrl(urlPath: Constants.URLs.loginPath)) else {
            fatalError("Invalid URL")
         }
        
        print("uri", url)
        
        let body: [String: String] = ["username": username, "password": password]

                let finalBody = try! JSONSerialization.data(withJSONObject: body)
                var request = URLRequest(url: url)
                request.httpMethod = "POST"
                request.httpBody = finalBody
                request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        
        return URLSession.shared.dataTaskPublisher(for: request)
            .map(\.data)
            .decode(type: LoginResponse.self, decoder: JSONDecoder())
            .map { [=12=].main }
            .receive(on: networkQueue)
            .eraseToAnyPublisher()
        
    }
    
}

那是我的 contentView

Button(action: {
                    self.counter += 1
                    print("count from action", self.counter)
                    
                
                    
                    func loaginTask() {
                        _ = loginService.doLoginTask(username: "1234567890", password: "12345")
                        .sink(
                          receiveCompletion: {
                            print("Received Completion: \([=13=])") },
                          receiveValue: { doctor in
                            print("hhhhh")
                          //  print("yes ", doctor.message as Any)
                            
                          }
                      )
                    }
                })

这就是我的 json 回复

{
    "success": true,
    "token": "ed48aa9b40c2d88079e6fd140c87ac61fc9ce78a",
    "expert-token": "6ec84e92ea93b793924d48aa9b40c2d88079e6fd140c87ac61fc9ce78ae4fa93",
    "message": "Logged in successfully"
}

Answer 1

由于取消，您的发布者在调用上下文下方被销毁，因为您没有保留对订阅者的引用。

要解决此问题，您必须在某处保留对订户的引用。最合适的变体在某些成员属性中，但是，作为变体，它也可以是独立的（如果符合您的目标），例如

func loaginTask() {
    var subscriber: AnyCancellable?
    subscriber = loginService.doLoginTask(username: "1234567890", password: "12345")
    .sink(
      receiveCompletion: { [subscriber] result in
        print("Received Completion: \(result)") 
        subscriber = nil                     // << keeps until completed
      },
      receiveValue: { doctor in
        print("hhhhh")
      //  print("yes ", doctor.message as Any)
        
      }
  )
}

Answer 2

首先，您的错误来自于您想要 return AnyPublisher<LoginModel, Error> 但您将响应映射为 .decode(type: LoginResponse.self, decoder: JSONDecoder())，这与您的 json 不匹配响应。

第二次，我将使用基本授权作为您的 URL 请求的主体，因为它是发送带有密码的用户凭据，必须保护密码。您可以访问服务器端吗？后端如何处理这个 post 请求？是授权还是内容类型？我会把这两个解决方案，尝试找到在服务器端设置的那个。

您的 LoginModel 必须与您的 json 响应匹配。我注意到他们缺少 expertToken：

struct LoginModel: Codable {

  let success: Bool
  let token: String
  let expertToken: String
  let message: String

  enum CodingKeys: String, CodingKey {
    case success
    case token
    case expertToken = "expert-token"
    case message
  }
}

所以我会这样创建 LoginService class：

final class LoginService {

  /// The request your use when the button is pressed.
  func logIn(username: String, password: String) -> AnyPublisher<LoginModel, Error> {

    let url = URL(string: "http://your.api.endpoints/")!
    let body = logInBody(username: username, password: password)
    let urlRequest = basicAuthRequestSetup(url: url, body: body)

    return URLSession.shared
      .dataTaskPublisher(for: urlRequest)
      .receive(on: DispatchQueue.main)
      .tryMap { try self.validate([=11=].data, [=11=].response) }
      .decode(
        type: LoginModel.self,
        decoder: JSONDecoder())
      .eraseToAnyPublisher()
  }

  /// The body for a basic authorization with encoded credentials.
  func logInBody(username: String, password: String) -> String {

    let body = String(format: "%@:%@",
                      username,
                      password)

    guard let bodyData = body.data(using: .utf8) else { return String() }

    let encodedBody = bodyData.base64EncodedString()
    return encodedBody
  }

  /// The authorization setup
  func basicAuthRequestSetup(url: URL, body: String) -> URLRequest {

    var urlRequest = URLRequest(url: url)
    urlRequest.httpMethod = "POST"
    urlRequest.setValue("Basic \(body)",
                        forHTTPHeaderField: "Authorization")

    return urlRequest
  }

  /// Validation of the Data and the response.
  /// You can handle response with status code for more precision.
  func validate(_ data: Data, _ response: URLResponse) throws -> Data {
    guard let httpResponse = response as? HTTPURLResponse else {
      throw NetworkError.unknown
    }
    guard (200..<300).contains(httpResponse.statusCode) else {
      throw networkRequestError(from: httpResponse.statusCode)
    }
    return data
  }

  /// Handle the status code errors to populate to user.
  func networkRequestError(from statusCode: Int) -> Error {
    switch statusCode {
    case 401:
      return NetworkError.unauthorized
    default:
      return NetworkError.unknown
    }
  }

  /// Define your different Error here that can come back from
  /// your backend.
  enum NetworkError: Error, Equatable {

    case unauthorized
    case unknown
  }
}

因此，如果您使用简单的 Content-Type，您的正文将是下面这个。从上面的代码替换 logInBody(username:password:) -> String 和 basicAuthRequestSetup(url:body:) -> URLRequest

/// Classic body for content type.
/// Keys must match the one in your server side.
func contentTypeBody(username: String, password: String) -> [String: Any] {
  [
    "username": username,
    "password": password
  ] as [String: Any]
}

/// Classic Content-Type but not secure. To avoid when having
/// passwords.
func contentTypeRequestSetup(url: URL,
                      body: [String: Any]) -> URLRequest {

  var urlRequest = URLRequest(url: url)
  urlRequest.httpMethod = "POST"
  urlRequest.setValue("application/json",
                      forHTTPHeaderField: "Content-Type")
  urlRequest.httpBody = try? JSONSerialization.data(withJSONObject: body)

  return urlRequest
}

然后我会创建一个 ViewModel 来处理将在您的视图中传递的逻辑。

final class OnboardingViewModel: ObservableObject {

  var logInService = LoginService()

  var subscriptions = Set<AnyCancellable>()

  func logIn() {
    logInService.logIn(username: "Shubhank", password: "1234")
      .sink(receiveCompletion: { completion in
              print(completion) },
            receiveValue: { data in
              print(data.expertToken) })  // This is your response
      .store(in: &subscriptions)
  }
}

现在，在您的 ContentView 中，您可以在按钮内传递视图模型登录操作：

struct ContentView: View {

  @ObservedObject var viewModel = OnboardingViewModel()

  var body: some View {
    Button(action: { viewModel.logIn() }) {
      Text("Log In")
    }
  }
}

无法使用与 SwiftUI 的组合从 URL 获得响应

Unable to get the response from URL using combine with SwiftUI

swiftui

combine