Facebook

expo-facebook provides Facebook integration, such as logging in through Facebook, for React Native apps. Expo exposes a minimal native API since you can access Facebook's Graph API directly through HTTP (using fetch, for example).

Platform Compatibility

Android Device	Android Emulator	iOS Device	iOS Simulator	Web
				Pending

Installation

expo install expo-facebook

If you're installing this in a bare React Native app, you should also follow these additional installation instructions.

For ejected (see: bare) apps, here are links to the iOS Installation Walkthrough and the Android Installation Walkthrough.

Configuration

Registering your app with Facebook

💡
When following these steps you will find on the Facebook Developer site that there are many fields and steps that you don't actually care about. Just look for the information that we ask you for and you will be OK!

Follow Facebook's developer documentation to register an application with Facebook's API and get an application ID. Take note of this application ID because it will be used as the appId option in your Facebook.logInWithReadPermissionsAsync call.

Then follow these steps based on the platforms you're targetting. This will need to be done from the Facebook developer site. You don't need to set up the iOS and Android standalone apps right away, you can do that at any time in the future if you just want to get the Expo client version running first.

No configuration is needed to use the Facebook SDK in the App Store Expo client, because all of your Facebook API calls will be made with Expo's Facebook App ID. The slight downside to this is that you can't customize which permissions your app requests from Facebook (like user_photos or user_friends), or integrate Facebook login with other services like Firebase auth. If you need that functionality, you have two options:

Build a standalone app
Build a custom Expo client app

Configure `app.json`

Add the field facebookScheme with your Facebook login redirect URL scheme found here under "4. Configure Your info.plist." It should look like "fb123456". If you do not do this, Facebook will not be able to redirect to your app after logging in.
Add the fields facebookAppId and facebookDisplayName, using your Facebook App ID and Facebook Display Name, respectively.
Optional fields
- facebookAutoInitEnabled, defaults to false
- facebookAutoLogAppEventsEnabled, defaults to Facebook's default policy (Only applies to standalone apps)
- facebookAdvertiserIDCollectionEnabled, defaults to Facebook's default policy (Only applies to standalone apps)

iOS Custom Expo client

Add your custom client's Bundle ID (shown in the output after running expo client:ios) in the app settings page pictured below. It should look something like: dev.expo.client.xxxxx

iOS standalone app

Add your app's Bundle ID as a Bundle ID in the app settings page pictured below.

Android standalone app

Build your standalone app for Android.
Run expo fetch:android:hashes.
Copy Facebook Key Hash and paste it as a key hash in your Facebook developer page pictured below.

You may have to switch the app from 'development mode' to 'public mode' on the Facebook developer page before other users can log in. This requires adding a privacy policy URL, which can be as simple as a GitHub Gist.

API

import * as Facebook from 'expo-facebook';

`Facebook.initializeAsync(appId: string | undefined, appName: string | undefined): Promise<void>`

Calling this method ensures that the SDK is initialized. You have to call this method before calling logInWithReadPermissionsAsync to ensure that Facebook support is initialized properly.

You may or may not provide an optional appId: string argument.

If you don't provide it, Facebook SDK will try to use appId from native app resources (which in standalone apps you would define in app.json, in Expo client are unavailable and in bare you configure yourself according to Facebook setup documentation for iOS and Android). If it fails to find one, the promise will be rejected.
If you provide an explicit appId, it will override any other source.

The same resolution mechanism works for appName.

`Facebook.setAutoInitEnabledAsync(enabled: boolean): Promise<void>`

Sets whether Facebook SDK should autoinitialize itself. SDK initialization involves eg. fetching app settings from Facebook or a profile of the logged in user. In some cases, you may want to disable or delay the SDK initialization, such as to obtain user consent or fulfill legal obligations. This method corresponds to this and this native SDK methods. Even though calling this method with enabled == true initializes the Facebook SDK on iOS, it does not on Android and we recommend always calling initializeAsync before performing any actions with effects that should be visible to the user (like loginWithPermissions).

In Expo, by default, autoinitialization of the Facebook SDK is disabled. You may change this value in runtime by calling this method or customize this feature in buildtime by setting appropriate app.json fields. The setting value is persisted across runs (value set with this method overriddes value from buildtime).

`Facebook.setAutoLogAppEventsEnabledAsync(enabled: boolean): Promise<void>`

Sets whether Facebook SDK should log app events. App events involve app eg. installs, app launches (more info here and here). In some cases, you may want to disable or delay the collection of automatically logged events, such as to obtain user consent or fulfill legal obligations. This method corresponds to this and this native SDK methods.

In Expo, by default, automatic logging app events is disabled. You may change this value in runtime by calling this method or customize this feature in buildtime by setting appropriate app.json fields. The setting value is persisted across runs (value set with this method overriddes value from buildtime).

`Facebook.setAdvertiserIDCollectionEnabledAsync(enabled: boolean): Promise<void>`

Sets whether Facebook SDK should collect and attach advertiser-id to sent events. advertiser-id let you identify and target specific customers. To learn more visit Facebook documentation describing that topic. In some cases, you may want to disable or delay the collection of advertiser-id, such as to obtain user consent or fulfill legal obligations. This method corresponds to this and this native SDK methods.

In Expo, by default, collecting those IDs is disabled. You may change this value in runtime by calling this method or customize this feature in buildtime by setting appropriate app.json fields. The setting value is persisted across runs (value set with this method overriddes value from buildtime).

`Facebook.logInWithReadPermissionsAsync(options)`

Prompts the user to log into Facebook and grants your app permission to access their Facebook data.

param object options

A map of options:

permissions (array) -- An array specifying the permissions to ask for from Facebook for this login. The permissions are strings as specified in the Facebook API documentation. The default permissions are ['public_profile', 'email'].

Returns

If the user or Facebook cancelled the login, returns { type: 'cancel' }.

Otherwise, returns { type: 'success', token, expires, permissions, declinedPermissions }. token is a string giving the access token to use with Facebook HTTP API requests. expires is the time at which this token will expire, as seconds since epoch. You can save the access token using, say, AsyncStorage, and use it till the expiration time. permissions is a list of all the approved permissions, whereas declinedPermissions is a list of the permissions that the user has rejected.

Example

async function logIn() {
  try {
    await Facebook.initializeAsync('<APP_ID>');
    const {
      type,
      token,
      expires,
      permissions,
      declinedPermissions,
    } = await Facebook.logInWithReadPermissionsAsync({
      permissions: ['public_profile'],
    });
    if (type === 'success') {
      // Get the user's name using Facebook's Graph API
      const response = await fetch(`https://graph.facebook.com/me?access_token=${token}`);
      Alert.alert('Logged in!', `Hi ${(await response.json()).name}!`);
    } else {
      // type === 'cancel'
    }
  } catch ({ message }) {
    alert(`Facebook Login Error: ${message}`);
  }
}

Given a valid Facebook application ID in place of <APP_ID>, the code above will prompt the user to log into Facebook then display the user's name. This uses React Native's fetch to query Facebook's Graph API.