Localization in React Native

 Localization is essential for making your React Native app accessible to a global audience. By supporting multiple languages, you ensure users from different regions have a seamless experience. Let’s start step by step.

Multiple language support

Step 1: Install Required Libraries

npm install i18next react-i18next react-native-localize

Step 2: Create Translation Files

Store translations in JSON files for each language. For example:
en.json (English):

{
  "welcome": "Welcome",
    "greeting": "Hello, {{name}}!"
}

bn.json (Bangali):

{
  "welcome": "স্বাগতম",
   "greeting": "হ্যালো, {{name}}!"
}

Step 3: Initialize i18next

import i18n from 'i18next';
import en from './locale-json/en.json';
import bn from './locale-json/bn.json';
import { initReactI18next } from 'react-i18next';
import { getLocales } from 'react-native-localize';

// Define the type for supported languages
export type TranslationKeys = keyof typeof en;

// Detect the device language
const getDeviceLanguage = (): string => {
  const locales = getLocales();
  return locales[0]?.languageTag || 'en';
};

// Initialize i18next
i18n.use(initReactI18next).init({
  compatibilityJSON: 'v4',
  resources: {
    en: { translation: en },
    bn: { translation: bn },
  },
  lng: getDeviceLanguage(),
  fallbackLng: 'en',
  interpolation: {
    escapeValue: false,
  },
});

export const i18nLocale = i18n;

Step 4: Wrap your app.js with the provider

import { I18nextProvider } from 'react-i18next';
import i18n from 'i18next';

const App = () => {
  return (
    <Provider store={store}>
      <PaperProvider>
        <I18nextProvider i18n={i18n}>
          <SafeAreaProvider>
            <Navigation />
          </SafeAreaProvider>
        </I18nextProvider>
      </PaperProvider>
    </Provider>
  );
};

Step 5: Make a hook to make it more useful

import { useMemo } from 'react';
import { i18nLocale } from '../locale/i18nLocale.ts';
import { AppString } from '../locale/AppString.ts';

type AppStringKey = keyof typeof AppString; // Keys of APP_STRING

export const useLocalization = () => {
  return useMemo(() => {
    const localizedStrings: Record<AppStringKey, string> = {} as Record<
      AppStringKey,
      string
    >;

    (Object.keys(AppString) as AppStringKey[]).forEach((key) => {
      localizedStrings[key] = i18nLocale.t(AppString[key]);
    });

    return localizedStrings;
  }, []);
};

export const AppString = {
  WELCOME: 'Welcome',
  GEETINGS: "Hello, {{name}}!"
}

Step 6: Use it in your component

const App = () => {
  const localization = useLocalization();

  return (
      <View>
        <Text>{localization.WELCOME}</Text>
      </View>
  );
};

export default App;

Ref:
GitHub: https://github.com/piashcse/react-native-movie
Medium: https://piashcse.medium.com/localization-in-react-native-a2a48e45cd27