Xcode内容预览无法输入@符号的技术求助

在Mac上使用Xcode的Content Preview测试带注册登录功能的SwiftUI App时，遇到以下问题：

• 按下Option+Q输入的是œ符号，而非@
• 从外部粘贴@符号也无法生效
• 导致邮箱格式验证失败，无法完成登录/注册流程

• 检查键盘布局：确认Mac系统的键盘布局为美式英文（美式布局下@的快捷键是Option+2），部分欧洲键盘布局会将œ映射到Option+Q，导致输入错误。可通过「系统设置-键盘-输入源」切换布局。
• 启用硬件键盘模拟：打开Xcode预览窗口，点击顶部菜单栏的「Editor」，勾选「Simulate Hardware Keyboard」，避免虚拟键盘的输入冲突。
• 重置Xcode预览缓存：按下Command+Option+P刷新预览，或直接重启Xcode，解决预览进程的缓存异常。
• 临时代码赋值测试：若仅需验证登录/注册逻辑，可直接在@State变量中预设带@的邮箱，比如：

  @State private var email: String = "test@example.com"
  

• 确认预览设备类型：确保预览的是iOS设备，而非Mac Catalyst目标，后者的键盘输入处理可能存在兼容性问题。

struct LoginView: View {
    @State private var email: String = ""
    @State private var password: String = ""
    @State private var isLoggedIn: Bool = false
    @State private var errorMessage: String = ""

    var body: some View {
        VStack(spacing: 20) {
            Text("My Project")
                .font(.largeTitle)
                .fontWeight(.bold)

            TextField("Email", text: $email)
                .textFieldStyle(RoundedBorderTextFieldStyle())
                .autocapitalization(.none)
                .keyboardType(.emailAddress)

            SecureField("Password", text: $password)
                .textFieldStyle(RoundedBorderTextFieldStyle())

            if !errorMessage.isEmpty {
                Text(errorMessage)
                    .foregroundColor(.red)
                    .font(.footnote)
            }

            Button(action: {
                loginUser()
            }) {
                Text("Login")
                    .frame(maxWidth: .infinity)
                    .padding()
                    .background(Color.blue)
                    .foregroundColor(.white)
                    .cornerRadius(10)
            }

            NavigationLink("Don't have an account? Register here.", value: "Register")
                .font(.footnote)

            NavigationLink(value: "CategorySelection") {
                EmptyView()
            }
            .navigationDestination(for: String.self) { destination in
                if destination == "CategorySelection" {
                    CategorySelectionView()
                } else if destination == "Register" {
                    RegistrationView()
                }
            }
            .disabled(!isLoggedIn)
        }
        .padding()
    }

    private func loginUser() {
        guard !email.isEmpty, !password.isEmpty else {
            errorMessage = "Please enter both email and password."
            return
        }

        Auth.auth().signIn(withEmail: email, password: password) { authResult, error in
            if let error = error {
                errorMessage = error.localizedDescription
            } else {
                errorMessage = ""
                isLoggedIn = true
            }
        }
    }
}

struct RegistrationView: View {
    @State private var email: String = ""
    @State private var password: String = ""
    @State private var errorMessage: String = ""
    @State private var isRegistered: Bool = false

    var body: some View {
        VStack(spacing: 20) {
            Text("Register")
                .font(.largeTitle)
                .fontWeight(.bold)

            TextField("Email", text: $email)
                .textFieldStyle(RoundedBorderTextFieldStyle())
                .autocapitalization(.none)
                .keyboardType(.emailAddress)

            SecureField("Password", text: $password)
                .textFieldStyle(RoundedBorderTextFieldStyle())

            if !errorMessage.isEmpty {
                Text(errorMessage)
                    .foregroundColor(.red)
                    .font(.footnote)
            }

            Button(action: {
                registerUser()
            }) {
                Text("Register")
                    .frame(maxWidth: .infinity)
                    .padding()
                    .background(Color.green)
                    .foregroundColor(.white)
                    .cornerRadius(10)
            }

            NavigationLink(value: "Login") {
                EmptyView()
            }
            .navigationDestination(for: String.self) { destination in
                if destination == "Login" {
                    LoginView()
                }
            }
            .disabled(!isRegistered)
        }
        .padding()
    }

    private func registerUser() {
        guard !email.isEmpty, !password.isEmpty else {
            errorMessage = "Please enter both email and password."
            return
        }

        Auth.auth().createUser(withEmail: email, password: password) { authResult, error in
            if let error = error {
                errorMessage = error.localizedDescription
            } else {
                errorMessage = ""
                isRegistered = true // 注册成功后跳转至LoginView
            }
        }
    }
}

内容的提问来源于stack exchange，提问作者László Bús