添加主题切换、多语言支持

i18n/index.ts

@@ -0,0 +1,55 @@
+import AsyncStorage from "@react-native-async-storage/async-storage";
+import * as Localization from "expo-localization";
+import i18n from "i18next";
+import { initReactI18next } from "react-i18next";
+
+import en from "./locales/en.json";
+import zh from "./locales/zh.json";
+
+const RESOURCES = {
+  en: { translation: en },
+  zh: { translation: zh },
+};
+
+const LANGUAGE_STORAGE_KEY = "user_language_preference";
+
+const initI18n = async () => {
+  let savedLanguage = null;
+  try {
+    savedLanguage = await AsyncStorage.getItem(LANGUAGE_STORAGE_KEY);
+  } catch (error) {
+    console.warn("Failed to load language preference", error);
+  }
+
+  // Get device language (e.g. "en-US" -> "en")
+  // Prefer Localization.getLocales()[0].languageCode; fall back to 'en'
+  const locales = Localization.getLocales?.() ?? [];
+  const deviceLanguageCode = locales[0]?.languageCode ?? "en";
+
+  const languageToUse = savedLanguage || deviceLanguageCode || "en";
+
+  i18n.use(initReactI18next).init({
+    resources: RESOURCES,
+    lng: languageToUse,
+    fallbackLng: "en",
+    interpolation: {
+      escapeValue: false,
+    },
+    react: {
+      useSuspense: false, // For React Native compatibility
+    },
+  });
+};
+
+initI18n();
+
+export default i18n;
+
+export const changeLanguage = async (lang: string) => {
+  try {
+    await i18n.changeLanguage(lang);
+    await AsyncStorage.setItem(LANGUAGE_STORAGE_KEY, lang);
+  } catch (error) {
+    console.warn("Failed to change/save language", error);
+  }
+};