comunicmobile/lib/utils/intl_utils.dart

import 'dart:convert';

import 'package:flutter/services.dart';
import 'package:intl/intl_standalone.dart';

/// Internationalization utilities
///
/// @author Pierre HUBERT

String _currLang;
Map<String, Map<String, String>> translations;

/// Initialize translations system
///
/// This method currently fetch the current user language
Future<void> initTranslations() async {
  _currLang = await findSystemLocale();

  // Load the list of translations
  final list = Map<String, String>.from(
      jsonDecode(await rootBundle.loadString("assets/langs.json")));

  translations = new Map();
  for (final entry in list.entries) {
    translations[entry.key] = Map<String, String>.from(jsonDecode(
        await rootBundle.loadString("assets/langs/${entry.value}.json")));
  }
}

/// Translate a string
///
/// Translate a given [string] into the current language, if available
///
/// Then apply the list of [args] to the string, each argument name is
/// surrounded by '%'
String tr(String string, {Map<String, String> args}) {
  // Check if a translation is available
  if (_currLang != null &&
      translations.containsKey(_currLang) &&
      translations[_currLang].containsKey(string))
    string = translations[_currLang][string];

  //Apply arguments
  if (args != null)
    args.forEach((key, value) => string = string.replaceAll("%$key%", value));

  return string;
}