在SwiftUI中SecureField获得焦点/未焦点时执行代码

import SwiftUI

struct ContentView: View {
    @State private var isFocused = false

    var body: some View {
        VStack {
            SecureField("Enter your password", text: $password)
                .focusable()
                .onAppear {
                    if self.isFocused {
                        print("SecureField is focused")
                        // 执行获得焦点时的代码
                    }
                }
                .onDisappear {
                    if !self.isFocused {
                        print("SecureField lost focus")
                        // 执行失去焦点时的代码
                    }
                }
                .onChange(of: isFocused) { newValue in
                    if newValue {
                        // SecureField 获得焦点
                    } else {
                        // SecureField 失去焦点
                    }
                }
        }
        .background(GeometryReader { geometry in
            Color.clear
                .preference(key: FocusPreferenceKey.self, value: isFocused)
        })
    }
}

struct FocusPreferenceKey: PreferenceKey {
    static var defaultValue: Bool = false

    static func reduce(value: inout Bool, nextValue: () -> Bool) {
        value = nextValue()
    }
}