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Sumary

See a complete video tutorial using flutter_facebook_auth (Spanish Only) https://www.youtube.com/watch?v=X-x5pHQ4Gz8&list=PLV0nOzdUS5XuWMzOCGZQPwCEZ1m5aZEo5


Installation

First, add flutter_facebook_auth as a dependency in your pubspec.yaml file.

flutter_facebook_auth: ^1.0.0

Android

Go to Facebook Login for Android - Quickstart

  1. Select an App or Create a New App

  2. Skip the step 2 (Download the Facebook App)

  3. Skip the step 3 (Integrate the Facebook SDK)

  4. Edit Your Resources and Manifest add this config in your android project

  • Open your /app/res/values/strings.xml file.

  • Add the following (replace {your-app-id} with your facebook app Id):

    <string name="facebook_app_id">{your-app-id}</string>
    <string name="fb_login_protocol_scheme">fb{your-app-id}</string>
    

    Here one example of strings.xml

    <?xml version="1.0" encoding="utf-8"?>
    <resources>
        <string name="app_name">Flutter Facebook Auth Example</string>
        <string name="facebook_app_id">1365719610250300</string>
        <string name="fb_login_protocol_scheme">fb1365719610250300</string>
    </resources>
    
  • Open the /app/manifest/AndroidManifest.xml file.

  • Add the following uses-permission element after the application element

    <uses-permission android:name="android.permission.INTERNET"/>
    
  • Add the following meta-data element, an activity for Facebook, and an activity and intent filter for Chrome Custom Tabs inside your application element

<meta-data android:name="com.facebook.sdk.ApplicationId"
       android:value="@string/facebook_app_id"/>

   <activity android:name="com.facebook.FacebookActivity"
       android:configChanges=
               "keyboard|keyboardHidden|screenLayout|screenSize|orientation"
       android:label="@string/app_name" />
   <activity
       android:name="com.facebook.CustomTabActivity"
       android:exported="true">
       <intent-filter>
           <action android:name="android.intent.action.VIEW" />
           <category android:name="android.intent.category.DEFAULT" />
           <category android:name="android.intent.category.BROWSABLE" />
           <data android:scheme="@string/fb_login_protocol_scheme" />
       </intent-filter>
   </activity>

Here one example of AndroidManifest.xml

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="app.meedu.flutter_facebook_auth_example">
   <uses-permission android:name="android.permission.INTERNET" />
   <application
       android:name="io.flutter.app.FlutterApplication"
       android:icon="@mipmap/ic_launcher"
       android:label="facebook auth">

       <meta-data
           android:name="com.facebook.sdk.ApplicationId"
           android:value="@string/facebook_app_id" />
       <activity
           android:name="com.facebook.FacebookActivity"
           android:configChanges="keyboard|keyboardHidden|screenLayout|screenSize|orientation"
           android:label="@string/app_name" />
       <activity
           android:name="com.facebook.CustomTabActivity"
           android:exported="true">
           <intent-filter>
               <action android:name="android.intent.action.VIEW" />

               <category android:name="android.intent.category.DEFAULT" />
               <category android:name="android.intent.category.BROWSABLE" />

               <data android:scheme="@string/fb_login_protocol_scheme" />
           </intent-filter>
       </activity>


       <activity
           android:name=".MainActivity"
           android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
           android:hardwareAccelerated="true"
           android:launchMode="singleTop"
           android:theme="@style/LaunchTheme"
           android:windowSoftInputMode="adjustResize">
           <meta-data
               android:name="io.flutter.embedding.android.NormalTheme"
               android:resource="@style/NormalTheme" />
           <meta-data
               android:name="io.flutter.embedding.android.SplashScreenDrawable"
               android:resource="@drawable/launch_background" />
           <intent-filter>
               <action android:name="android.intent.action.MAIN" />
               <category android:name="android.intent.category.LAUNCHER" />
           </intent-filter>
       </activity>
       <meta-data
           android:name="flutterEmbedding"
           android:value="2" />
   </application>
</manifest>
  1. Associate Your Package Name and Default Class with Your App
  1. Provide the Development and Release Key Hashes for Your App

    To find info to how to generate you key hash go to https://developers.facebook.com/docs/facebook-login/android?locale=en_US#6--provide-the-development-and-release-key-hashes-for-your-app

    Note: if your application uses Google Play App Signing then you should get certificate SHA-1 fingerprint from Google Play Console and convert it to base64

    You should add key hashes for every build variants like release, debug, CI/CD, etc.


Also if you want to add support for express login on Android go to https://developers.facebook.com/docs/facebook-login/android/#expresslogin

Check the example project to see a correct set up.


iOS

You need Swift support<br/> The plugin is written in Swift, so your project needs to have Swift support enabled. If you've created the project using flutter create -i swift [projectName] you are all set. If not, you can enable Swift support by opening the project with XCode, then choose File -> New -> File -> Swift File. XCode will ask you if you wish to create Bridging Header, click yes.

  • In your Podfile uncomment the next line (You need set the minimum target to 9.0 or higher)

    platform :ios, '9.0'
    
  • Go to Facebook Login for iOS - Quickstart and select or create your app.

  • Skip the step 2 (Set up Your Development Environment).

  • In the step 3 (Register and Configure Your App with Facebook) you need add your Bundle Identifier

    You can find you Bundle Identifier in Xcode (Runner - Target Runner - General)

    image

  • In the Step 4 you need configure your Info.plist file inside ios/Runner/Info.plist

    From Xcode you can open your Info.plist as Source Code now add the next code and replace {your-app-id} with your facebook app Id.

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>fb{your-app-id}</string>
    </array>
  </dict>
</array>
<key>FacebookAppID</key>
<string>{your-app-id}</string>
<key>FacebookDisplayName</key>
<string>{your-app-name}</string>
<key>LSApplicationQueriesSchemes</key>
<array>
  <string>fbapi</string>
  <string>fb-messenger-share-api</string>
  <string>fbauth2</string>
  <string>fbshareextension</string>
</array>

If you have implement another providers (Like Google) in your app you should merge values in Info.plist

Check if you already have CFBundleURLTypes or LSApplicationQueriesSchemes keys in your Info.plist. If you have, you should merge their values, instead of adding a duplicate key.

Example with Google and Facebook implemetation:

<key>CFBundleURLTypes</key>
<array>
  <dict>
    <key>CFBundleTypeRole</key>
    <string>Editor</string>
    <key>CFBundleURLSchemes</key>
    <array>
      <string>fb{your-app-id}</string>
      <string>com.googleusercontent.apps.{your-app-specific-url}</string>
    </array>
  </dict>
</array>

To use any of the Facebook dialogs (e.g., Login, Share, App Invites, etc.) that can perform an app switch to Facebook apps, your application's Info.plist also needs to include: ...)

<key>LSApplicationQueriesSchemes</key>
<array>
  <string>fbapi</string>
  <string>fbapi20130214</string>
  <string>fbapi20130410</string>
  <string>fbapi20130702</string>
  <string>fbapi20131010</string>
  <string>fbapi20131219</string>
  <string>fbapi20140410</string>
  <string>fbapi20140116</string>
  <string>fbapi20150313</string>
  <string>fbapi20150629</string>
  <string>fbapi20160328</string>
  <string>fbauth</string>
  <string>fb-messenger-share-api</string>
  <string>fbauth2</string>
  <string>fbshareextension</string>
</array>

NOTE

for Objective-C projects (correctly works is not granted because this plugin was written with swift)


METHODS

Just use FacebookAuth.instance. NOTE: all methods are asynchronous.

  • FacebookAuth.instance.login() : request login with a list of permissions.
  Future<void> _login() async {
    try {
        // by default the login method has the next permissions ['email','public_profile']
      AccessToken accessToken = await FacebookAuth.instance.login();
      print(accessToken.toJson());
      // get the user data
      final userData = await FacebookAuth.instance.getUserData();
      print(auserData);
    } on FacebookAuthException catch (e) {
      print(e.message);
      switch (e.errorCode) {
          case FacebookAuthErrorCode.OPERATION_IN_PROGRESS:
            print("You have a previous login operation in progress");
            break;
          case FacebookAuthErrorCode.CANCELLED:
            print("login cancelled");
            break;
          case FacebookAuthErrorCode.FAILED:
            print("login failed");
            break;
      }
    }
  }

The public_profile permission allows you read the next fields id, first_name, last_name, middle_name, name, name_format, picture, short_name

For more info go to https://developers.facebook.com/docs/facebook-login/permissions/

  • .logOut() : close the current facebook session.

  • .isLogged : check if the user has an active facebook session. The response will be null if the user is not logged.

    Expected response one instance of AccessToken class:

    {
      "userId": "300333249307438",
      "token": "FACEBOOK_TOKEN",
      "expires": "2021-01-09T09:06:10.749",
      "lastRefresh": "2020-11-10T11:44:05.749",
      "applicationId": "1365719610250300",
      "graphDomain": "facebook",
      "isExpired": false,
      "grantedPermissions": ["email", "user_link"],
      "declinedPermissions": []
    }
    

    Example

    Future<void> _checkIfIsLogged() async {
      final AccessToken accessToken = await FacebookAuth.instance.isLogged;
      if (accessToken != null) {
        print("is Logged:::: ${prettyPrint(accessToken.toJson())}");
        // now you can call to  FacebookAuth.instance.getUserData();
        final userData = await FacebookAuth.instance.getUserData();
        // final userData = await FacebookAuth.instance.getUserData(fields: "email,birthday,friends,gender,link");
      }
    }
    
  • .getUserData({String fields = "name,email,picture"}) : get the user info only if the user is logged.

Only call this method if you have an user Logged

Expected response Map<String,dynamic>:

{
email = "dsmr.apps@gmail.com";
id = 3003332493073668;
name = "Darwin Morocho";
picture =     {
    data =         {
        height = 50;
        "is_silhouette" = 0;
        url = "https://platform-lookaside.fbsbx.com/platform/profilepic/?asid=3003332493073668&height=50&width=50&ext=1570917120&hash=AeQMSBD5s4QdgLoh";
        width = 50;
    };
};
}

EXAMPLE

import 'dart:convert';
import 'package:flutter/cupertino.dart';
import 'package:flutter/material.dart';
import 'package:flutter_facebook_auth/flutter_facebook_auth.dart';

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

String prettyPrint(Map json) {
  JsonEncoder encoder = new JsonEncoder.withIndent('  ');
  String pretty = encoder.convert(json);
  return pretty;
}

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Map<String, dynamic> _userData;
  AccessToken _accessToken;
  bool _checking = true;

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

  Future<void> _checkIfIsLogged() async {
    final AccessToken accessToken = await FacebookAuth.instance.isLogged;
    setState(() {
      _checking = false;
    });
    if (accessToken != null) {
      print("is Logged:::: ${prettyPrint(accessToken.toJson())}");
      // now you can call to  FacebookAuth.instance.getUserData();
      final userData = await FacebookAuth.instance.getUserData();
      // final userData = await FacebookAuth.instance.getUserData(fields: "email,birthday,friends,gender,link");
      _accessToken = accessToken;
      setState(() {
        _userData = userData;
      });
    }
  }

  void _printCredentials() {
    print(
      prettyPrint(_accessToken.toJson()),
    );
  }

  Future<void> _login() async {
    try {
      // show a circular progress indicator
      setState(() {
        _checking = true;
      });
      _accessToken = await FacebookAuth.instance.login(); // by the fault we request the email and the public profile
      // loginBehavior is only supported for Android devices, for ios it will be ignored
      // _accessToken = await FacebookAuth.instance.login(
      //   permissions: ['email', 'public_profile', 'user_birthday', 'user_friends', 'user_gender', 'user_link'],
      //   loginBehavior:
      //       LoginBehavior.DIALOG_ONLY, // (only android) show an authentication dialog instead of redirecting to facebook app
      // );
      _printCredentials();
      // get the user data
      // by default we get the userId, email,name and picture
      final userData = await FacebookAuth.instance.getUserData();
      // final userData = await FacebookAuth.instance.getUserData(fields: "email,birthday,friends,gender,link");
      _userData = userData;
    } on FacebookAuthException catch (e) {
      // if the facebook login fails
      print(e.message); // print the error message in console
      // check the error type
      switch (e.errorCode) {
        case FacebookAuthErrorCode.OPERATION_IN_PROGRESS:
          print("You have a previous login operation in progress");
          break;
        case FacebookAuthErrorCode.CANCELLED:
          print("login cancelled");
          break;
        case FacebookAuthErrorCode.FAILED:
          print("login failed");
          break;
      }
    } catch (e, s) {
      // print in the logs the unknown errors
      print(e);
      print(s);
    } finally {
      // update the view
      setState(() {
        _checking = false;
      });
    }
  }


  Future<void> _logOut() async {
    await FacebookAuth.instance.logOut();
    _accessToken = null;
    _userData = null;
    setState(() {});
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(
          title: const Text('Facebook Auth Example'),
        ),
        body: _checking
            ? Center(
                child: CircularProgressIndicator(),
              )
            : SingleChildScrollView(
                child: Padding(
                  padding: const EdgeInsets.all(8.0),
                  child: Column(
                    crossAxisAlignment: CrossAxisAlignment.center,
                    children: <Widget>[
                      Text(
                        _userData != null ? prettyPrint(_userData) : "NO LOGGED",
                      ),
                      SizedBox(height: 20),
                      _accessToken != null
                          ? Text(
                              prettyPrint(_accessToken.toJson()),
                            )
                          : Container(),
                      SizedBox(height: 20),
                      CupertinoButton(
                        color: Colors.blue,
                        child: Text(
                          _userData != null ? "LOGOUT" : "LOGIN",
                          style: TextStyle(color: Colors.white),
                        ),
                        onPressed: _userData != null ? _logOut : _login,
                      ),
                      SizedBox(height: 50),
                    ],
                  ),
                ),
              ),
      ),
    );
  }
}

Using with firebase_auth

import 'package:firebase_auth/firebase_auth.dart';
.
.
.
.


final FirebaseAuth _auth = FirebaseAuth.instance;
.
.
.

 // this line do auth in firebase with your facebook credential. Just pass your facebook token (String)
 final OAuthCredential credential =  FacebookAuthProvider.credential( _accessToken.token); // _token is your facebook access token as a string

// FirebaseUser is deprecated
final User user = (await _auth.signInWithCredential(credential)).user;

Libraries

flutter_facebook_auth