為什么我的@State 對象不保留它們的值？

Question

我正在嘗試創建一個基本的注冊屏幕。 屏幕顯示正常，但是當我單擊提交並返回錯誤時， @State變量（例如$viewModel.firstName和$lastname重置回空字符串，因此我的用戶丟失了所有進度。

注冊屏幕

struct SignUpScreen: View {

    @State
    var firstName: String = ""
    @State
    var lastName: String = ""
    @State
    var birthday: String = ""
    @State
    var number: String = ""
    @State
    var email: String = ""
    @State
    var password: String = ""
    @State
    var confirmPassword: String = ""

    @ObservedObject
    var viewModel: SignUpViewModel = SignUpViewModel()


    var body: some View {
        ZStack {
            VStack {
                VClearBackground()
                Spacer()
            }
            ScrollView {
                VStack(alignment: .leading) {
                    Group {
                        PreHeaderText(header: "Get Started")
                            .alignmentGuide(.leading, computeValue: {d in
                                d[.leading]
                            })
                            .padding(EdgeInsets.init(top: 32, leading: 0, bottom: 0, trailing: 0))
                        HeaderText(header: "Create Account")
                        EditText(hint: "John", text: $viewModel.firstName, label: "FIRST NAME", textContentType: UITextContentType.name)
                        EditText(hint: "Doe", text: $lastName, label: "LAST NAME", textContentType: UITextContentType.name)
                        EditText(hint: "01/01/2001", text: $birthday, label: "BIRTHDAY")
                        EditText(hint: "(123) 456-7890)", text: $number, label: "MOBILE NUMBER", textContentType: UITextContentType.telephoneNumber, keyboardType: UIKeyboardType.phonePad)
                        EditText(hint: "email@exmaple.com", text: $email, label: "EMAIL", textContentType: UITextContentType.emailAddress)
                        EditText(hint: "********", text: $password, label: "PASSWORD", textContentType: UITextContentType.newPassword)
                        EditText(hint: "********", text: $confirmPassword, label: "CONFIRM PASSWORD", textContentType: UITextContentType.newPassword)
                    }
                    Group {
                        if self.viewModel.error != nil {
                            HStack {
                                Spacer()
                                Text(viewModel.error ?? "")
                                    .foregroundColor(ColorTheme.error.color)
                                Spacer()
                            }
                            .padding()
                        }
                        HStack {
                            Spacer()
                            VowerButton(text: "Submit") {
                                self.viewModel.signUp(firstName: self.viewModel.firstName, lastName: self.lastName, email: self.email, birthday: self.birthday, phoneNumber: self.number, password: self.password, confirmPassword: self.confirmPassword)
                            }
                            Spacer()
                        }
                        .padding()

                        HStack {
                            Spacer()
                            NavigationLink(destination: LoginScreen(), isActive: $viewModel.goToLogin) {
                                CtaText(text: "Have an account?", cta: "Login") {
                                    self.viewModel.onGoToLoginClicked()
                                }
                            }
                            .padding()
                            Spacer()
                        }

                        Spacer()
                    }
                }
            }
            .padding(EdgeInsets.init(top: 16, leading: 16, bottom: 16, trailing: 16))
            .frame(maxWidth: .infinity, maxHeight: .infinity, alignment: .leading)
        }
        .background(LinearGradient(gradient: Gradient(colors: [.black, ColorTheme.brandPurple.color]), startPoint: .top, endPoint: .bottom))
        .edgesIgnoringSafeArea(.all)
    }
}

注冊 ViewModel

class SignUpViewModel : ObservableObject {
    @State
    var firstName: String = ""

    @Published
    var error: String? = nil

    @Published
    var goHome: Bool = false

    @Published
    var goToLogin: Bool = false

    func onGoToLoginClicked() {
        self.goToLogin = true
    }

    func signUp(firstName: String, lastName: String, email: String, birthday: String, phoneNumber: String, password: String, confirmPassword: String) {
        if (firstName.count < 3) {
            error = "Please enter first name"
            return
        }
        if (lastName.count < 3) {
            error = "Please enter last name"
            return
        }
        if (!email.isEmail()) {
            error = "Pleaes enter valid email"
            return
        }
        if (birthday.isEmpty) {
            error = "Pleae enter valid birthday"
            return
        }
        if (!phoneNumber.isDigits) {
            error = "Please enter valid phone number"
            return
        }
        if (password.count < 8) {
            error = "Please enter a password that is at least 8 characters long"
        }
        if (password != confirmPassword) {
            error = "Password do not match"
        }
        Auth.auth().createUser(withEmail: email, password: password, completion: { authResult, error in
            if authResult != nil {
                self.goHome = true
            } else {
                self.error = error?.localizedDescription
            }
        })
    }
}

編輯文本視圖

struct EditText: View {

    var hint: String
    @Binding
    var text: String
    var label: String = ""
    var defaultValue =  ""
    var textContentType: UITextContentType? = .none
    var keyboardType: UIKeyboardType = .default

    private func initializeDefaultValue() {
        DispatchQueue.main.async {
            self.text = self.defaultValue
        }
    }

    var body: some View {
        initializeDefaultValue()
        return VStack(alignment: .leading) {
            Text(label).font(.system(size: 12)).bold()
                .foregroundColor(ColorTheme.text.color)
            HStack {
                TextField(hint, text: $text)
                .lineLimit(1)
                .textContentType(textContentType)
                .keyboardType(keyboardType)
                    .foregroundColor(ColorTheme.text.color)
            }
            Divider().background(Color(ColorTheme.brandBlue.value))
        }
        .padding(EdgeInsets.init(top: 12, leading: 0, bottom: 8, trailing: 0))
    }
}

Answer 1

好的，現在我明白了（繼續你的第二個問題，我首先回答了這個問題）。 @State應該在專為它設計的View中使用。 在ObservableObject你必須使用@Published ，所以下面是它應該如何

class SignUpViewModel : ObservableObject {
    @Published
    var firstName: String = ""