Flutter – Saving Data in Local using Shared Preferences

This simple example demonstrates saving an integer value in the local shared preferences.
We will use a flutter plugin called shared_preferences for this.
You can read more about the plugin from here.

Add Dependency

First thing is to add the package to the dependencies.
Go to pubspec.yaml and add the package.

dependencies:
  flutter:
    sdk: flutter
  shared_preferences: "0.4.3"

Example

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

class PreferenceDemo extends StatefulWidget {
  PreferenceDemo({Key key, this.title}) : super(key: key);
  final String title;

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

class _PreferenceDemo extends State<PreferenceDemo> {
  int _counter = 0;

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

  //Loading counter value on start
  _loadCounter() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      _counter = (prefs.getInt('counter') ?? 0);
    });
  }

  //Incrementing counter after click
  _incrementCounter() async {
    SharedPreferences prefs = await SharedPreferences.getInstance();
    setState(() {
      _counter = (prefs.getInt('counter') ?? 0) + 1;
      prefs.setInt('counter', _counter);
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Saved counter in Preferences and Reloaded...',
            ),
            Text(
              '$_counter',
              style: Theme.of(context).textTheme.display1,
            ),
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}