shared_preferences

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

dependencies:
  shared_preferences: ^0.5.3+4

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

void main() {
  runApp(MaterialApp(
    home: Scaffold(
      body: Center(
      child: RaisedButton(
        onPressed: _incrementCounter,
        child: Text('Increment Counter'),
        ),
      ),
    ),
  ));
}

_incrementCounter() async {
  SharedPreferences prefs = await SharedPreferences.getInstance();
  int counter = (prefs.getInt('counter') ?? 0) + 1;
  print('Pressed $counter times.');
  await prefs.setInt('counter', counter);
}

url_launcher

Flutter plugin for launching a URL on Android and iOS. Supports web, phone, SMS, and email schemes.

dependencies:
  url_launcher: ^5.1.2

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

void main() {
  runApp(Scaffold(
    body: Center(
      child: RaisedButton(
        onPressed: _launchURL,
        child: Text('Show Flutter homepage'),
      ),
    ),
  ));
}

_launchURL() async {
  const url = 'https://flutter.dev';
  if (await canLaunch(url)) {
    await launch(url);
  } else {
    throw 'Could not launch $url';
  }
}

path_provider

Flutter plugin for getting commonly used locations on the Android & iOS file systems, such as the temp and app data directories.

dependencies:
  path_provider: ^1.3.0

Directory tempDir = await getTemporaryDirectory();
String tempPath = tempDir.path;

Directory appDocDir = await getApplicationDocumentsDirectory();
String appDocPath = appDocDir.path;