SwiftUI中UserDefault.set后列表未实时更新，求排查实现问题

你的代码核心问题是视图没有监听歌曲数据的变化：每次渲染body时调用getSongs()读取UserDefaults，但SwiftUI只会在状态变量变化时自动刷新视图。修改完歌词后，UserDefaults的数据确实更新了，但视图没收到“需要刷新”的信号，所以必须重新进入页面才会重新读取数据。

需要用状态变量存储歌曲列表，修改歌词后同步更新这个状态变量，触发视图自动刷新。具体步骤如下：

• 添加状态变量存储歌曲列表，替代每次从UserDefaults读取
• 在视图出现时加载初始数据
• 修改updateLyrics方法，更新UserDefaults后同步更新状态变量
• 优化数据读取的错误处理，避免强制解包崩溃

struct LyricEditView: View {
    @State private var songs: [Song] = []
    @State private var selectedSong: Song?
    @State private var lyricsText = ""
    @State private var isEditingLyrics = false

    var body: some View {
        VStack {
            List {
                // 直接遍历状态变量songs，而非每次调用getSongs()
                ForEach(songs, id: \.id) { song in
                    Button(action: {
                        selectedSong = song
                        lyricsText = song.lyrics
                        isEditingLyrics = true
                    }) {
                        HStack {
                            Text(song.title)
                            Spacer()
                            Text(song.artist)
                        }
                    }
                }
            }
            .sheet(isPresented: $isEditingLyrics) {
                VStack {
                    TextField("Lyrics", text: $lyricsText)
                    Button("Save", action: {
                        guard let selectedSong = selectedSong else { return }
                        updateLyrics(song: selectedSong)
                    })
                }
            }
            // 视图出现时加载初始歌曲数据
            .onAppear {
                songs = getSongs()
            }
        }
    }

    func getSongs() -> [Song] {
        let defaults = UserDefaults(suiteName: "group.lyric_group")
        guard let data = defaults?.data(forKey: "songs"),
              let decodedSongs = try? JSONDecoder().decode([Song].self, from: data) else {
            // 读取失败返回空数组，避免崩溃
            return []
        }
        return decodedSongs
    }

    func updateLyrics(song: Song) {
        let defaults = UserDefaults(suiteName: "group.lyric_group")

        guard var updatedSongs = try? JSONDecoder().decode([Song].self, from: defaults?.data(forKey: "songs") ?? Data()),
              let songIndex = updatedSongs.firstIndex(where: { $0.id == song.id }) else {
            isEditingLyrics = false
            return
        }

        // 修改对应歌曲的歌词
        updatedSongs[songIndex].lyrics = lyricsText

        // 编码并写入UserDefaults
        let encoder = JSONEncoder()
        if let encoded = try? encoder.encode(updatedSongs) {
            defaults?.set(encoded, forKey: "songs")
            // 更新状态变量，触发视图刷新
            songs = updatedSongs
        }

        isEditingLyrics = false
    }
}

// 需确保Song模型符合Identifiable和Codable协议
struct Song: Identifiable, Codable {
    let id: UUID
    let title: String
    let artist: String
    var lyrics: String
}

• 用firstIndex(where:)替代循环查找，代码更简洁高效
• 去掉try!改用guard let处理解码失败，避免运行时崩溃
• 视图直接使用状态变量驱动UI，符合SwiftUI的数据流原则

内容的提问来源于stack exchange，提问作者Yro