check react native ios local code example
Example: ios react native detect locale
import { NativeModules, Platform } from 'react-native'
const locale = Platform.select({
ios: NativeModules.SettingsManager?.settings?.AppleLocale || NativeModules.SettingsManager?.settings?.AppleLanguages[0],
android: NativeModules.I18nManager.localeIdentifier,
})