SwiftUI更改SecureField屏蔽字符

MacOS 11 上的 SwiftUI

目標是讓 SwiftUI SecureField 顯示不同于默認專案符號 (??????) 的 Unicode 字符，例如表情符號、隨機生成的字符等。目標的一個重要部分是實際的文本輸入由用戶完全可編輯和保留，并且可以在@State變數中訪問，并且僅顯示屏蔽字符，但我不介意它是通過 TextField 還是其他一些視圖來實作的。

例如，香草 SecureField 專案符號：

struct ContentView : View {

  @State var password : String = ""

  var body: some View {

    VStack {
      SecureField("Password", text: $password)
      Button("Transmogrify!") {}
    }.padding()

  }
}

這導致：

目標是實作與 SecureField 相同的行為，但顯示不同的字符，如下所示：

到目前為止，我還沒有想出一個有效的代碼示例。我曾嘗試將普通TextField與顯式結合使用Binding<String>來嘗試控制底層文本get/set但由于系結的性質會影響最終存盤在password

uj5u.com熱心網友回復：

你可以用代理來做

import SwiftUI
//Shows a sample use
struct SecureParentView: View{
    @State var text: String = "secure"
    var body: some View{
        VStack{
            Text(text)
            MySecureFieldView(text: $text)
        }
    }
}
//The custom field
struct MySecureFieldView: View {
    @Binding var text: String
    //The proxy handles the masking
    var proxy: Binding<String>{
        Binding(get: {
            //Replace the return value
            var result = ""
            for _ in 0..<text.count{
                let char: Character = "\u{272A}"
                result.append(char)
            }
            return result
        }, set: { value in
            if value.isEmpty{
                text = value
            } else if value.count < text.count{
                //If the user deletes more than 1 character
                if text.count - value.count == 1{
                    text.removeLast()
                }else{
                    text = ""
                }
            } else if value.count > text.count{
                //If the user adds more than 1 character
                if value.count - text.count == 1{
                    let new = (value.last?.description) ?? ""
                    text.append(contentsOf: new)
                }else{
                    text = ""
                }
            }
        })
    }
    var body: some View {
        TextField("test", text: proxy)
    }
}

struct SecureParentView_Previews: PreviewProvider {
    static var previews: some View {
        SecureParentView()
    }
}

對于 iOS 15、MacCatalyst 15 和 macOS 12，有一個稍微更好的解決方案。

//The custom field
@available(iOS 15.0, macOS 12.0, *)
struct MySecureFieldView: View {
    @Binding var text: String
    //The proxy handles the masking
    var proxy: Binding<String>{
        Binding(get: {
            //Replace the return value
            var result = ""
            for _ in 0..<text.count{
                let char: Character = "\u{272A}"
                result.append(char)
            }
            return result
        }, set: { value in
            //Not needed here because the TextField is focused
        })
    }
    @FocusState private var focusedField: Int?
    var body: some View {
        //This is for size. The 3 layers have to match so the cursor doesn't look off
        Text(text)
            .overlay(
                ZStack{
                    //This is the regular textfield to hold the data
                    TextField("actual", text: $text)
                        .foregroundColor(Color(UIColor.clear))
                        .focused($focusedField, equals: 1)
                    //This will sit on top and is the only one that has color
                    //It will reduce in size to match lettering
                    Text(proxy.wrappedValue)
                        .minimumScaleFactor(0.2)
                        .foregroundColor(Color(UIColor.label))
                }
            )
            .foregroundColor(Color(UIColor.clear))
            .textSelection(.disabled)//You likely dont want this
            .onTapGesture {
                focusedField = 1
            }
    }
    
}

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