shared_preferences 2.3.1

Flutter plugin for reading and writing simple key-value pairs. Wraps NSUserDefaults on iOS and SharedPreferences on Android.

example/lib/main.dart

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

// ignore_for_file: public_member_api_docs

import 'dart:async';

import 'package:flutter/material.dart';
import 'package:shared_preferences/shared_preferences.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      title: 'SharedPreferencesWithCache Demo',
      home: SharedPreferencesDemo(),
    );
  }
}

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

  @override
  SharedPreferencesDemoState createState() => SharedPreferencesDemoState();
}

class SharedPreferencesDemoState extends State<SharedPreferencesDemo> {
  final Future<SharedPreferencesWithCache> _prefs =
      SharedPreferencesWithCache.create(
          cacheOptions: const SharedPreferencesWithCacheOptions(
              // This cache will only accept the key 'counter'.
              allowList: <String>{'counter'}));
  late Future<int> _counter;
  int _externalCounter = 0;

  Future<void> _incrementCounter() async {
    final SharedPreferencesWithCache prefs = await _prefs;
    final int counter = (prefs.getInt('counter') ?? 0) + 1;

    setState(() {
      _counter = prefs.setInt('counter', counter).then((_) {
        return counter;
      });
    });
  }

  /// Gets external button presses that could occur in another instance, thread,
  /// or via some native system.
  Future<void> _getExternalCounter() async {
    final SharedPreferencesAsync prefs = SharedPreferencesAsync();
    setState(() async {
      _externalCounter = (await prefs.getInt('externalCounter')) ?? 0;
    });
  }

  @override
  void initState() {
    super.initState();
    _counter = _prefs.then((SharedPreferencesWithCache prefs) {
      return prefs.getInt('counter') ?? 0;
    });

    _getExternalCounter();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('SharedPreferencesWithCache Demo'),
      ),
      body: Center(
          child: FutureBuilder<int>(
              future: _counter,
              builder: (BuildContext context, AsyncSnapshot<int> snapshot) {
                switch (snapshot.connectionState) {
                  case ConnectionState.none:
                  case ConnectionState.waiting:
                    return const CircularProgressIndicator();
                  case ConnectionState.active:
                  case ConnectionState.done:
                    if (snapshot.hasError) {
                      return Text('Error: ${snapshot.error}');
                    } else {
                      return Text(
                        'Button tapped ${snapshot.data ?? 0 + _externalCounter} time${(snapshot.data ?? 0 + _externalCounter) == 1 ? '' : 's'}.\n\n'
                        'This should persist across restarts.',
                      );
                    }
                }
              })),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}