SharedPreferences: تخزين البيانات البسيطة بنظام المفتاح والقيمة

flutter pub add shared_preferences

import 'package:shared_preferences/shared_preferences.dart';

class SettingsPage extends StatefulWidget {
  const SettingsPage({super.key});

  @override
  State<SettingsPage> createState() => _SettingsPageState();
}

class _SettingsPageState extends State<SettingsPage> {
  bool _darkMode = false;
  String _username = '';

  @override
  void initState() {
    super.initState();
    _loadPreferences();
  }

  Future<void> _loadPreferences() async {
    final prefs = await SharedPreferences.getInstance();
    setState(() {
      _darkMode = prefs.getBool('dark_mode') ?? false;
      _username = prefs.getString('username') ?? '';
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('الإعدادات')),
      body: Column(
        children: [
          Text('مرحباً، $_username'),
          Switch(
            value: _darkMode,
            onChanged: (value) async {
              final prefs = await SharedPreferences.getInstance();
              await prefs.setBool('dark_mode', value);
              setState(() => _darkMode = value);
            },
          ),
        ],
      ),
    );
  }
}

Future<void> saveUserData() async {
  final prefs = await SharedPreferences.getInstance();

  // الكتابة
  await prefs.setString('username', 'إدريس');
  await prefs.setInt('launch_count', 42);
  await prefs.setDouble('font_size', 16.5);
  await prefs.setBool('notifications_enabled', true);
  await prefs.setStringList('recent_searches', ['flutter', 'dart', 'firebase']);

  // القراءة مع قيم افتراضية آمنة من الفراغ
  final username = prefs.getString('username') ?? 'زائر';
  final launches = prefs.getInt('launch_count') ?? 0;
  final fontSize = prefs.getDouble('font_size') ?? 14.0;
  final notifs = prefs.getBool('notifications_enabled') ?? true;
  final searches = prefs.getStringList('recent_searches') ?? [];

  print('$username فتح التطبيق $launches مرة');
}

Future<void> handleLogout() async {
  final prefs = await SharedPreferences.getInstance();

  // حذف مفتاح واحد
  await prefs.remove('auth_token');

  // أو مسح كل شيء (استخدم بحذر)
  await prefs.clear();
}

// التحقق من وجود مفتاح قبل القراءة
Future<void> checkOnboarding() async {
  final prefs = await SharedPreferences.getInstance();
  final hasSeenOnboarding = prefs.containsKey('onboarding_complete');
  if (!hasSeenOnboarding) {
    // عرض تدفق التأهيل
  }
}

class PreferencesService {
  static const _kDarkMode = 'dark_mode';
  static const _kUsername = 'username';
  static const _kLaunchCount = 'launch_count';

  Future<SharedPreferences> get _prefs => SharedPreferences.getInstance();

  Future<bool> getDarkMode() async =>
      (await _prefs).getBool(_kDarkMode) ?? false;

  Future<void> setDarkMode(bool value) async =>
      (await _prefs).setBool(_kDarkMode, value);

  Future<String> getUsername() async =>
      (await _prefs).getString(_kUsername) ?? 'زائر';

  Future<void> setUsername(String name) async =>
      (await _prefs).setString(_kUsername, name);

  Future<int> incrementLaunchCount() async {
    final p = await _prefs;
    final count = (p.getInt(_kLaunchCount) ?? 0) + 1;
    await p.setInt(_kLaunchCount, count);
    return count;
  }
}