SwiftUI中如何在应用设置里即时切换语言无需重启？

问题原因 #

当前实现仅将选中语言保存到UserDefaults，但LocalizedStringKey会在视图初始化时一次性解析，不会监听语言变化；同时没有通知所有视图刷新，导致必须重启应用才能生效。

解决步骤 #

1. 创建语言管理类 #

实现一个ObservableObject统一管理语言状态，触发视图刷新并提供本地化字符串：

import SwiftUI

class LanguageManager: ObservableObject {
    static let shared = LanguageManager()
    
    @Published var currentLanguage: String {
        didSet {
            UserDefaults.standard.set(currentLanguage, forKey: "language")
        }
    }
    
    init() {
        currentLanguage = UserDefaults.standard.string(forKey: "language") 
                          ?? Locale.preferredLanguages.first 
                          ?? "en"
    }
    
    // 获取对应语言的资源包
    var localizedBundle: Bundle {
        let path = Bundle.main.path(forResource: currentLanguage, ofType: "lproj") 
                   ?? Bundle.main.path(forResource: "en", ofType: "lproj")!
        return Bundle(path: path)!
    }
    
    // 获取本地化字符串
    func localizedString(for key: String) -> String {
        NSLocalizedString(key, bundle: localizedBundle, comment: "")
    }
}

2. 在App入口注入环境对象 #

让所有视图都能访问语言管理实例：

@main
struct YourAppName: App {
    var body: some Scene {
        WindowGroup {
            ContentView()
                .environmentObject(LanguageManager.shared)
        }
    }
}

3. 重构语言设置页面 #

简化代码逻辑，使用语言管理类的状态而非本地@State：

struct Languages: View {
    @State private var showingAlert = false
    @Environment(\.presentationMode) var mode
    @EnvironmentObject var languageManager: LanguageManager
    
    // 语言选项列表，简化重复代码
    private let languageOptions: [(code: String, name: String)] = [
        ("en", "English"),
        ("ru", "Русский"),
        ("fr", "Français"),
        ("es", "Español"),
        ("ko", "한국어"),
        ("ja", "日本語"),
        ("zh-Hans", "简体中文"),
        ("id", "Indonesia"),
        ("pt-BR", "Português (Brasil)"),
        ("it", "Italiano"),
        ("de", "Deutsch")
    ]
    
    var body: some View {
        VStack(alignment: .leading) {
            // 使用本地化标题
            DoubleTextView(
                topText: LocalizedStringKey(languageManager.localizedString(for: "languages")),
                buttomText: "",
                topTextSize: 24,
                buttomTextSize: 0
            )
            
            // 遍历生成语言切换按钮
            ForEach(languageOptions, id: \.code) { option in
                ZStack {
                    Toggle(isOn: Binding(
                        get: { languageManager.currentLanguage == option.code },
                        set: { isOn in
                            languageManager.currentLanguage = isOn ? option.code : (Locale.preferredLanguages.first ?? "en")
                        }
                    )) {
                        Text(option.name)
                            .foregroundColor(.white)
                            .font(.custom("Manrope-Bold", size: 16))
                    }
                    .padding(.horizontal)
                    .toggleStyle(SwitchToggleStyle(tint: Color("active")))
                }
                .padding(.vertical, 10)
                .background(Rectangle()
                    .fill(Color("navigation"))
                    .frame(height: 50)
                    .cornerRadius(8))
            }
        }
        .alert(isPresented: $showingAlert) {
            Alert(
                title: Text(languageManager.localizedString(for: "later")),
                primaryButton: .destructive(Text(languageManager.localizedString(for: "Ok"))) {
                    // 可选：请求刷新场景替代强制退出
                    UIApplication.shared.requestSceneSessionRefresh(nil)
                },
                secondaryButton: .cancel(Text(languageManager.localizedString(for: "laterButton")))
            )
        }
        .background(
            Image("background2")
                .resizable()
                .scaledToFill()
                .edgesIgnoringSafeArea(.all)
                .frame(width: UIScreen.main.bounds.width, height: UIScreen.main.bounds.height)
        )
        .onChange(of: languageManager.currentLanguage) { _ in
            showingAlert = true
        }
        .padding(.top, 40)
        .overlay (
            HStack {
                Button {
                    mode.wrappedValue.dismiss()
                } label: {
                    Image(systemName: "arrow.left")
                        .foregroundColor(.white)
                        .font(.system(size: 24))
                }
                Spacer()
            }
            .padding(.horizontal, 3.0)
            .frame(maxHeight: .infinity, alignment: .top)
        )
        .navigationBarTitle("", displayMode: .inline)
        .navigationBarHidden(true)
        .padding(.horizontal, 10.0)
    }
}

4. 全局替换本地化文本使用方式 #

将所有直接使用LocalizedStringKey的地方，改为通过LanguageManager获取本地化字符串，比如自定义通用组件：

struct LocalizedText: View {
    let key: String
    @EnvironmentObject var languageManager: LanguageManager
    
    var body: some View {
        Text(languageManager.localizedString(for: key))
    }
}

// 使用示例：LocalizedText(key: "welcome_message")

关键说明 #

• @Published属性会在语言变化时自动通知所有依赖的视图重新渲染
• 自定义localizedBundle确保加载选中语言的本地化资源文件
• 避免使用exit(0)强制退出，改用requestSceneSessionRefresh更符合iOS应用规范

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