use system language

src/screens/Startup/Startup.tsx

@@ -1,15 +1,25 @@
 import React, { useEffect } from 'react';
-import { ActivityIndicator, View } from 'react-native';
+import { ActivityIndicator, View, NativeModules, Platform } from 'react-native';
+import { useTranslation } from 'react-i18next';
 import { useTheme } from '../../hooks';
 import { Brand } from '../../components';
 import PoweredByFlux from '../../components/PoweredByFlux/PoweredByFlux';
 import { setDefaultTheme } from '../../store/theme';
 import { ApplicationScreenProps } from '../../../@types/navigation';
 
 const Startup = ({ navigation }: ApplicationScreenProps) => {
+  const { i18n } = useTranslation();
   const { Layout, Gutters } = useTheme();
 
   const init = async () => {
+    const deviceLanguage =
+      Platform.OS === 'ios'
+        ? NativeModules.SettingsManager.settings.AppleLocale ||
+          NativeModules.SettingsManager.settings.AppleLanguages[0] // iOS 13
+        : NativeModules.I18nManager.localeIdentifier;
+
+    console.log(deviceLanguage); // en_US
+    await i18n.changeLanguage(deviceLanguage.split('_')[0].split('-')[0]); // use system language
     await new Promise((resolve) =>
       setTimeout(() => {
         resolve(true);

src/translations/resources/index.ts

@@ -1,2 +1,2 @@
 export { default as en } from './en/_index';
-export { default as fr } from './fr/_index';
+export { default as id } from './id/_index';