2. Automatically saving & restoring the selected locale

Flutter Translate can automatically save the selected locale and restore it after application restart.

This can be done by passing an implementation of ITranslatePreferences during delegate creation:

 var delegate = await LocalizationDelegate.create(
      ...
        preferences: TranslatePreferences()
      ...

Example implementation using the shared_preferences package:

import 'dart:ui';
import 'package:flutter_translate/flutter_translate.dart';
import 'package:shared_preferences/shared_preferences.dart';

class TranslatePreferences implements ITranslatePreferences
{
    static const String _selectedLocaleKey = 'selected_locale';

    @override
    Future<Locale> getPreferredLocale() async
    {
        final preferences = await SharedPreferences.getInstance();

        if(!preferences.containsKey(_selectedLocaleKey)) return null;

        var locale = preferences.getString(_selectedLocaleKey);

        return localeFromString(locale);
    }

    @override
    Future savePreferredLocale(Locale locale) async
    {
        final preferences = await SharedPreferences.getInstance();

        await preferences.setString(_selectedLocaleKey, localeToString(locale));
    }
}

And don't forget to reference the shared_preferences package in pubspec.yaml

dependencies:
  shared_preferences: <latest version>