SwiftUI 结合 ViewModel 电子邮件验证

Question

如何使用 combine 验证合并这两个代码的视图模型中的电子邮件？

这是在我的 RegisterViewModel 里面

private var isEmailValidPublisher: ValidatePublisher {
        $email
            .removeDuplicates()
            .map { [=10=].trimmingCharacters(in: .whitespacesAndNewlines).count >= 10}
            .handleEvents(receiveOutput: { [weak self] in [=10=] ? (self?.emailMessage = "") : (self?.emailMessage = "Invalid email")})
            .eraseToAnyPublisher()
    }

我想在 isEmailValidPublisher 中添加此验证。

func isValidEmail() -> Bool {
        let emailRegEx = "(?:[\p{L}0-9!#$%\&'*+/=?\^_`{|}~-]+(?:\.[\p{L}0-9!#$%\&'*+/=?\^_`{|}" + "~-]+)*|\"(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21\x23-\x5b\x5d-\" + "x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])*\")@(?:(?:[\p{L}0-9](?:[a-" + "z0-9-]*[\p{L}0-9])?\.)+[\p{L}0-9](?:[\p{L}0-9-]*[\p{L}0-9])?|\[(?:(?:25[0-5" + "]|2[0-4][0-9]|[01]?[0-9][0-9]?)\.){3}(?:25[0-5]|2[0-4][0-9]|[01]?[0-" + "9][0-9]?|[\p{L}0-9-]*[\p{L}0-9]:(?:[\x01-\x08\x0b\x0c\x0e-\x1f\x21" + "-\x5a\x53-\x7f]|\\[\x01-\x09\x0b\x0c\x0e-\x7f])+)\])"
        
        let emailValidation = NSPredicate(format:"SELF MATCHES[c] %@", emailRegEx)
        return emailValidation.evaluate(with: self)
    }

我如何将它们混合在 isEmailValidPublisher 中，以便我可以在我的注册视图中使用该信息，如下所示

 Image(systemName: "envelope")
                    .foregroundColor(registerVM.emailMessage != "" ? .red: .blue)

Answer 1

假设您有一个像这样的简单视图：

struct ContentView: View {
    
    @StateObject var controller = Controller()
    
    var body: some View {
        VStack {
            TextField("email", text: $controller.email)
                .foregroundColor(controller.inputValid ? .primary : .red)
            controller.validationMessage.map { message in
                Text(message)
                    .foregroundColor(.red)
            }
        }
    }
}

并且您想在 ObservableObject 中包含逻辑：

class Controller: ObservableObject {
    
    @Published var email = ""
    @Published private(set) var validationMessage: String?
    
    var inputValid: Bool {
        validationMessage == nil
    }
    
    
    init() {
        // you subscribe to any changes to the email field input
        $email
        // you ignore the first empty value that it gets initialised with
            .dropFirst()
        // you give the user a bit of time to finish typing
            .debounce(for: 0.6, scheduler: RunLoop.main)
        // you get rid of duplicated inputs as they do not change anything in terms of validation
            .removeDuplicates()
        // you validate the input string and in case of problems publish an error message 
            .map { input in
                guard !input.isEmpty else {
                    return "Email cannot be left empty"
                }
                guard input.isValidEmail() else {
                    return "Email is not valid"
                }
        // in case the input is valid the error message is nil
                return nil
            }
        // you publish the error message for the view to react to
            .assign(to: &$validationMessage)
    }
}

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