import 'dart:convert'; import 'package:shared_preferences/shared_preferences.dart'; class StorageUtil { StorageUtil._internal(); static final StorageUtil _instance = StorageUtil._internal(); factory StorageUtil(){ return _instance; } SharedPreferences? prefs; Future init() async{ prefs = await SharedPreferences.getInstance(); } Future setJSON(String key,var jsonVal){ String jsonString = jsonEncode(jsonVal); return prefs!.setString(key, jsonString); } getJSON(String key){ String? jsonString = prefs?.getString(key); return jsonString == null?null:jsonDecode(jsonString); } Future setBool(String key,bool value){ return prefs!.setBool(key, value); } bool? getBool(String key){ return prefs!.getBool(key); } Future remove(String key){ return prefs!.remove(key); } }