SwiftUI MVVM 如何设置从 ViewModel 函数到 View 的回调

Question

我正在使用 MVVM 设置登录页面逻辑，但在从 ViewModel 调用该函数后，我无法弄清楚如何修改用户登录状态。

登录查看

struct LoginView: View {
    @ObservedObject var user: User
    @ObservedObject var viewModel = LoginViewModel()
    @State var inputUser: String = ""
    @State var inputPass: String = ""
    
    var body: some View {
        ScrollView {
            VStack(alignment: .leading) {
                Group {
                    Text("Login")
                    CustomTextField(placeHolder: "Username", value: $viewModel.user, secure: false)
                    CustomTextField(placeHolder: "Password", value: $viewModel.pass, secure: true)
                    Button(action: {
                        self.viewModel.login()
                        // After this login function completes and if return result success
                        // How do I pass data / callback after login?
                        // How to check if login success then set token or login failed
                        self.user.tokenIsActive = true
                    }) {
                        Text("Sign In")
                    }
                }
            }
        }
    }
}

登录视图模型

class LoginViewModel: ObservableObject, LoginService {
    var apiSession: APIService
    
    @Published var user = ""
    @Published var pass = ""
    
    @Published var accessToken: String?
    
    var cancellables = Set<AnyCancellable>()
    
    init(apiSession: APIService = APISession()) {
        self.apiSession = apiSession
    }
    
    func login() {
        let cancellable = self.loginUser(user: user, pass: pass)
            .sink(receiveCompletion: { result in
                switch result {
                case .failure(let error):
                    print("Handle error: \(error)")
                case .finished:
                    break
                }
                
            }) { (result) in
                self.accessToken = result.accessToken
                UserDefaults.standard.set(self.accessToken, forKey: "accessToken")
        }
        cancellables.insert(cancellable)
    }
}

用户

所以我将用户会话存储在 User 类中

class User: ObservableObject {
    @Published var tokenIsActive = false;
}

如何从视图模型中的登录功能传递数据并检查登录是否成功并设置用户令牌？提前谢谢你。

Answer 1

使用完成块并更新您的状态。

func login(_ completion: @escaping ((Bool)->Void)) {
    let cancellable = self.loginUser(user: user, pass: pass)
        .sink(receiveCompletion: { result in
            switch result {
            case .failure(let error):
                print("Handle error: \(error)")
            case .finished:
                break
            }
            
        }) { (result) in
            completion(true)
            self.accessToken = result.accessToken
            UserDefaults.standard.set(self.accessToken, forKey: "accessToken")
    }
    cancellables.insert(cancellable)
}

使用：

self.viewModel.login { (isSuccess) in
    if isSuccess {
        self.user.tokenIsActive = true
    }
}