SwiftUI列表选中播放音频：@State变量didSet未触发的问题排查

首先明确：@State属性的didSet不会被SwiftUI的状态更新触发。因为SwiftUI的@State包装器会直接操作底层存储值，完全绕过属性的setter和didSet逻辑，所以你写的didSet永远不会执行，这就是核心问题。

以下是几种可行的解决方法：

方法1：使用.onChange修饰符（最直接） #

这是SwiftUI官方推荐的监听状态变化方式，直接在视图上添加监听逻辑，当selectedSound更新时执行播放操作：

import SwiftUI

struct SoundList: View {
    let category: Category
    @State private var selectedSound: String?

    var body: some View {
        VStack {
            Text(selectedSound ?? "N/A")
            List(category.sounds, id: \.self, selection: $selectedSound) { sound in
                Text(sound)
            }
        }
        .navigationTitle(category.name)
        // 监听selectedSound的变化，执行播放逻辑
        .onChange(of: selectedSound) { newValue in
            if let sound = newValue {
                AudioManager.shared.playAudio(withFilename: sound)
            }
        }
    }
}

方法2：将状态移至ViewModel（适合复杂业务场景） #

如果后续需要扩展更多音频相关逻辑，建议把状态和业务操作分离到ViewModel中，用@Published属性触发变化：

import SwiftUI
import Combine

class SoundViewModel: ObservableObject {
    @Published var selectedSound: String? {
        didSet {
            if let sound = selectedSound {
                AudioManager.shared.playAudio(withFilename: sound)
            }
        }
    }
    let category: Category
    
    init(category: Category) {
        self.category = category
    }
}

struct SoundList: View {
    @StateObject private var viewModel: SoundViewModel

    init(category: Category) {
        _viewModel = StateObject(wrappedValue: SoundViewModel(category: category))
    }

    var body: some View {
        VStack {
            Text(viewModel.selectedSound ?? "N/A")
            List(viewModel.category.sounds, id: \.self, selection: $viewModel.selectedSound) { sound in
                Text(sound)
            }
        }
        .navigationTitle(viewModel.category.name)
    }
}

方法3：直接在列表项点击事件中处理 #

如果不需要持久化selectedSound状态，只是单纯播放音频，可以直接给列表项添加点击手势，跳过状态绑定：

import SwiftUI

struct SoundList: View {
    let category: Category
    @State private var selectedSound: String?

    var body: some View {
        VStack {
            Text(selectedSound ?? "N/A")
            List(category.sounds, id: \.self) { sound in
                Text(sound)
                    .onTapGesture {
                        selectedSound = sound
                        AudioManager.shared.playAudio(withFilename: sound)
                    }
            }
        }
        .navigationTitle(category.name)
    }
}

内容的提问来源于stack exchange，提问作者Mrugesh Tank