@gocodingnow/rn-native-base-boilerplate/template/src/i18n/setup.ts

React Native + Native Base Boilerplate

import 'intl-pluralrules'
import i18n from 'i18next'
import RNLocalize from 'react-native-localize'
import {I18nManager} from 'react-native'
import {initReactI18next} from 'react-i18next'
import en from './translations/en.json'
import {Storage} from '@utils/mmkv'
import {LOG} from '@utils/logger'
import {LOCALE} from '@constants/app'

const DEFAULT_RTL = false
const DEFAULT_LOCALE = 'en'

const LANGUAGES = {
  en: {
    translation: en,
  },
}

const LANG_CODES = Object.keys(LANGUAGES)
const defaultLanguage = {languageTag: DEFAULT_LOCALE, isRTL: DEFAULT_RTL}

const LANGUAGE_DETECTOR = {
  type: 'languageDetector',
  async: true,
  detect: callback => {
    function setDefaultLanguage() {
      const {languageTag, isRTL} =
        RNLocalize.findBestAvailableLanguage(LANG_CODES) || defaultLanguage
      // update layout direction
      I18nManager.forceRTL(isRTL)
      callback(languageTag)
    }

    Storage.instance
      .getItem(LOCALE, 'string')
      .then((language: string) => {
        if (!language) {
          throw new Error('No language is set, choosing English as fallback')
        }
        callback(language)
      })
      .catch((error: any) => {
        // if error fetching stored data or no language was stored
        // display errors when in DEV mode as console statements
        LOG.error(error.message)
        setDefaultLanguage()
      })
  },
  init: () => {
    //
  },
  cacheUserLanguage: language => {
    Storage.instance.setItem(LOCALE, language)
  },
}

export const setI18nConfig = () => {
  // clear translation cache
  try {
    i18n
      // detect language
      .use(LANGUAGE_DETECTOR as any)
      // pass the i18n instance to react-i18next.
      .use(initReactI18next)
      // set options
      .init({
        resources: LANGUAGES,
        react: {
          useSuspense: false,
        },
        fallbackLng: 'en',
        interpolation: {
          escapeValue: false,
        },
      })
  } catch (error) {}
}

export const getLocale = () => {
  // fallback if no available language fits
  const {languageTag} = RNLocalize.findBestAvailableLanguage(LANG_CODES) || defaultLanguage
  return languageTag
}