Flutter Facebook Login

main.dart

import 'package:flutter/material.dart';
import 'package:flutter_facebook_login/flutter_facebook_login.dart';
import 'package:http/http.dart' as http;
import 'dart:convert';
import 'package:flutter_auth_buttons/flutter_auth_buttons.dart';

void main() => runApp(MyApp());

class MyApp extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    // TODO: implement createState
    return _MyAppState();
  }
}

class _MyAppState extends State<MyApp> {
  bool _isLoggedIn = false;
  Map userDetails;
  final facebookLogin = FacebookLogin();

  _loginWithFB() async {
    final result = await facebookLogin.logIn(['email']);

    switch (result.status) {
      case FacebookLoginStatus.loggedIn:
        final token = result.accessToken.token;
        final graphResponse = await http.get(
            'https://graph.facebook.com/v2.12/me?fields=name,picture,email&access_token=${token}');
        final details = jsonDecode(graphResponse.body);
        print(details);
        setState(() {
          userDetails = details;
          _isLoggedIn = true;
        });
        break;

      case FacebookLoginStatus.cancelledByUser:
        setState(() => _isLoggedIn = false);
        break;
      case FacebookLoginStatus.error:
        setState(() => _isLoggedIn = false);
        break;
    }
  }

  _logout() {
    facebookLogin.logOut();
    setState(() {
      _isLoggedIn = false;
    });
  }

  @override
  Widget build(BuildContext context) {
    // TODO: implement build
    return MaterialApp(
      home: Scaffold(
        body: Center(
            child: _isLoggedIn
                ? Column(
                    mainAxisAlignment: MainAxisAlignment.center,
                    children: <Widget>[
                      Image.network(
                        userDetails["picture"]["data"]["url"],
                        height: 50.0,
                        width: 50.0,
                      ),
                      Text(userDetails["name"]),
                      FlatButton(
                        color: Colors.blue[600],
                        child: Text("Logout"),
                        onPressed: () {
                          _logout();
                        },
                      )
                    ],
                  )
                : Center(
                    child: FacebookSignInButton(
                      onPressed: () {
                        _loginWithFB();
                      },
                    ),
                  )),
      ),
    );
  }
}