如何快速回传方法处理程序

Question

我是Swift的新手，目前，我正在实现验证代码的UI，但我不知道该怎么做。我发现了一些类似于我对StackOverflow的要求的东西，我只是复制并传递到我的项目中，然后正如您在VerificationView_Previews中看到的，我们需要将方法处理程序传回我不知道如何传递帮助，请

//
//  VerificationView.swift
//  UpdateHistory
//
//  Created by Admin on 4/21/21.
//

import SwiftUI

public struct VerificationView: View {

var maxDigits: Int = 6
var label = "Enter One Time Password"
@State var pin: String = ""
@State var showPin = true
var handler: (String, (Bool) -> Void) -> Void
public var body: some View {
    VStack {
        Text(label).font(.title)
        ZStack {
            pinDots
            backgroundField
        }
    }
}
private var pinDots: some View {
    HStack {
        Spacer()
        ForEach(0..<maxDigits) { index in
            Image(systemName: self.getImageName(at: index))
                .font(.system(size: 60, weight: .thin, design: .default))
            Spacer()
        }
    }
}

private func getImageName(at index: Int) -> String {
    if index >= self.pin.count {
        return "square"
    }
    if self.showPin {
        return self.pin.digits[index].numberString + ".square"
    }
    return "square"
}

private var backgroundField: some View {
    let boundPin = Binding<String>(get: { self.pin }, set: { newValue in
        self.pin = newValue
        self.submitPin()
    })
    
    return TextField("", text: boundPin, onCommit: submitPin)
        .accentColor(.clear)
        .foregroundColor(.clear)
        .keyboardType(.numberPad)
}


private var showPinButton: some View {
    Button(action: {
        self.showPin.toggle()
    }, label: {
        self.showPin ?
            Image(systemName: "eye.slash.fill").foregroundColor(.primary) :
            Image(systemName: "eye.fill").foregroundColor(.primary)
    })
}

private func submitPin() {
    if pin.count == maxDigits {
        handler(pin) { isSuccess in
            if isSuccess {
                print("pin matched, go to next page, no action to perfrom here")
            } else {
                pin = ""
                print("this has to called after showing toast why is the failure")
              }
           }
        }
    }
}
extension String {
var digits: [Int] {
    var result = [Int]()
    for char in self {
        if let number = Int(String(char)) {
            result.append(number)
        }
    }
    return result
   }
}

extension Int {

var numberString: String {
    
    guard self < 10 else { return "0" }
    
    return String(self)
   }
}

struct VerificationView_Previews: PreviewProvider {
    static var previews: some View {
        VerificationView() // need to pass method handler
    }

}

Answer 1

为了查看目的，您可以简单地使用如下所示。预览不需要第二个参数

struct VerificationView_Previews: PreviewProvider {
    
    static var previews: some View {
        VerificationView { (pin, _) in
            print(pin)
        }
    }
}

也可以这样使用

struct VerificationView_Previews: PreviewProvider {
    
    var successClosure: (Bool) -> Void
    
    static var previews: some View {
        VerificationView { (pin, successClosure) in
            
        }
    }
}