Send messages to multiple devices on iOS

Firebase Cloud Messaging provides two ways to target a message to multiple devices:

  • Topic messaging, which allows you to send a message to multiple devices that have opted in to a particular topic.
  • Device group messaging, which allows you to send a single message to multiple instances of an app running on devices belonging to a group.

This tutorial focuses on sending topic messages from your app server using the HTTP or XMPP protocols for FCM, and receiving and handling them in an iOS app. This page lists all the steps to achieve this, from setup to verification — so it may cover steps you already completed if you have set up an iOS client app for FCM or worked through the steps to Send your First Message.

Add Firebase to your iOS project

This section covers tasks you may have completed if you have already enabled other Firebase features for your app. For FCM specifically, you'll need to upload your APNs authentication key and register for remote notifications.

Prerequisites

  • Install the following:

    • Xcode 10.3 or later
    • CocoaPods 1.4.0 or later

  • Make sure that your project meets the following requirements:

    • Your project must target iOS 8 or later.
    • Swift projects must use Swift 3.0 or later.

  • Set up a physical iOS device or the iOS simulator for running your app.

    • For Cloud Messaging, complete the following tasks:

      • Set up a physical iOS device.
      • Obtain an Apple Push Notification Authentication Key for your Apple Developer account.
      • Enable Push Notifications in XCode under App > Capabilities.

    • For all other Firebase products, you can use either a physical iOS device or the iOS simulator.

  • Sign into Firebase using your Google account.

If you don't already have an Xcode project and just want to try out a Firebase product, you can download one of our quickstart samples.

Create a Firebase project

Before you can add Firebase to your iOS app, you need to create a Firebase project to connect to your iOS app. Visit Understand Firebase Projects to learn more about Firebase projects.

Register your app with Firebase

After you have a Firebase project, you can add your iOS app to it.

Visit Understand Firebase Projects to learn more about best practices and considerations for adding apps to a Firebase project, including how to handle multiple build variants.

  1. In center of the Firebase console's project overview page, click the iOS icon (plat_ios) to launch the setup workflow.

    If you've already added an app to your Firebase project, click Add app to display the platform options.

  2. Enter your app's bundle ID in the iOS bundle ID field. Find your bundle ID, as follows:

    1. Open your app in XCode.

    2. Select the top-level app in the project navigator, then select the General tab.

      The value of the Bundle Identifier field is the iOS bundle ID (for example, com.yourcompany.yourproject).

  3. (Optional) Enter other app information as prompted by the setup workflow.

  4. Click Register app.

Add a Firebase configuration file

  1. Click Download GoogleService-Info.plist to obtain your Firebase iOS config file (GoogleService-Info.plist).

    • You can download your Firebase iOS config file again at any time.

    • Make sure the config file is not appended with additional characters, like (2).

  2. Move your config file into the root of your Xcode project. If prompted, select to add the config file to all targets.

If you have multiple bundle IDs in your project, you must associate each bundle ID with a registered app in the Firebase console so that each app can have its own GoogleService-Info.plist file.

Add Firebase SDKs to your app

We recommend using CocoaPods to install the Firebase libraries. However, if you'd rather not use CocoaPods, you can integrate the SDK frameworks directly.

Note that if you're using one of the quickstart samples, the Xcode project and Podfile (with pods) are already present, but you'll still need to add your Firebase configuration file and install the pods.

You can add any of the supported Firebase products to your iOS app.

  1. Create a Podfile if you don't already have one:

    cd your-project-directory
    pod init

  2. To your Podfile, add the Firebase pods that you want to use in your app.

    For an optimal experience with Firebase Cloud Messaging, we recommend enabling Google Analytics in your project. Also, as part of setting up Analytics, you need to add the Firebase SDK for Analytics to your app.

    Analytics enabled 

    # Add the Firebase pod for Google Analytics
pod 'Firebase/Analytics'
    
# Add the pod for Firebase Cloud Messaging
pod 'Firebase/Messaging'

    Analytics not enabled 

    # Add the pod for Firebase Cloud Messaging
pod 'Firebase/Messaging'

  3. Install the pods, then open your .xcworkspace file to see the project in Xcode:

    pod install
    open your-project.xcworkspace

Upload your APNs authentication key

Upload your APNs authentication key to Firebase. If you don't already have an APNs authentication key, see Configuring APNs with FCM.

  1. Inside your project in the Firebase console, select the gear icon, select Project Settings, and then select the Cloud Messaging tab.

  2. In APNs authentication key under iOS app configuration, click the Upload button.

  3. Browse to the location where you saved your key, select it, and click Open. Add the key ID for the key (available in Certificates, Identifiers & Profiles in the Apple Developer Member Center) and click Upload.

Initialize Firebase in your app

You'll need to add Firebase initialization code to your application. Import the Firebase module and configure a shared instance as shown:

  1. Import the Firebase module in your UIApplicationDelegate:

    Swift

    import Firebase

    Objective-C

    @import Firebase;
  2. Configure a FirebaseApp shared instance, typically in your app's application:didFinishLaunchingWithOptions: method:

    Swift

    // Use Firebase library to configure APIs
FirebaseApp.configure()

    Objective-C

    // Use Firebase library to configure APIs
[FIRApp configure];

Register for remote notifications

Either at startup, or at the desired point in your application flow, register your app for remote notifications. Call registerForRemoteNotifications as shown:

Swift

if #available(iOS 10.0, *) {
  // For iOS 10 display notification (sent via APNS)
  UNUserNotificationCenter.current().delegate = self

  let authOptions: UNAuthorizationOptions = [.alert, .badge, .sound]
  UNUserNotificationCenter.current().requestAuthorization(
    options: authOptions,
    completionHandler: {_, _ in })
} else {
  let settings: UIUserNotificationSettings =
  UIUserNotificationSettings(types: [.alert, .badge, .sound], categories: nil)
  application.registerUserNotificationSettings(settings)
}

application.registerForRemoteNotifications()

AppDelegate.swift

Objective-C

if ([UNUserNotificationCenter class] != nil) {
  // iOS 10 or later
  // For iOS 10 display notification (sent via APNS)
  [UNUserNotificationCenter currentNotificationCenter].delegate = self;
  UNAuthorizationOptions authOptions = UNAuthorizationOptionAlert |
      UNAuthorizationOptionSound | UNAuthorizationOptionBadge;
  [[UNUserNotificationCenter currentNotificationCenter]
      requestAuthorizationWithOptions:authOptions
      completionHandler:^(BOOL granted, NSError * _Nullable error) {
        // ...
      }];
} else {
  // iOS 10 notifications aren't available; fall back to iOS 8-9 notifications.
  UIUserNotificationType allNotificationTypes =
  (UIUserNotificationTypeSound | UIUserNotificationTypeAlert | UIUserNotificationTypeBadge);
  UIUserNotificationSettings *settings =
  [UIUserNotificationSettings settingsForTypes:allNotificationTypes categories:nil];
  [application registerUserNotificationSettings:settings];
}

[application registerForRemoteNotifications];
AppDelegate.m

Subscribe the client app to a topic

Client apps can subscribe to any existing topic, or they can create a new topic. When a client app subscribes to a new topic name (one that does not already exist for your Firebase project), a new topic of that name is created in FCM and any client can subsequently subscribe to it.

To subscribe to a topic, call the subscription method from your application's main thread (FCM is not thread-safe). If the subscription request fails initially, FCM retries automatically. For cases where the subscription cannot be completed, the subscription throws an error that you can catch in a completion handler as shown:

Swift

Messaging.messaging().subscribe(toTopic: "weather") { error in
  print("Subscribed to weather topic")
}
ViewController.swift

Objective-C

[[FIRMessaging messaging] subscribeToTopic:@"weather"
                                completion:^(NSError * _Nullable error) {
  NSLog(@"Subscribed to weather topic");
}];
ViewController.m

This call makes an asynchronous request to the FCM backend and subscribes the client to the given topic. Before calling subscribeToTopic:topic, make sure that the client app instance has already received a registration token via the callback didReceiveRegistrationToken.

Each time the app starts, FCM makes sure that all requested topics have been subscribed. To unsubscribe, call unsubscribeFromTopic:topic, and FCM unsubscribes from the topic in the background.

Receive and handle topic messages

FCM delivers topic messages in the same way as other downstream messages.

Implement AppDelegate application:didReceiveRemoteNotification: as shown:

Swift

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // Messaging.messaging().appDidReceiveMessage(userInfo)

  // Print message ID.
  if let messageID = userInfo[gcmMessageIDKey] {
    print("Message ID: \(messageID)")
  }

  // Print full message.
  print(userInfo)
}

func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                 fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // Messaging.messaging().appDidReceiveMessage(userInfo)

  // Print message ID.
  if let messageID = userInfo[gcmMessageIDKey] {
    print("Message ID: \(messageID)")
  }

  // Print full message.
  print(userInfo)

  completionHandler(UIBackgroundFetchResult.newData)
}
AppDelegate.swift

Objective-C

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[FIRMessaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);
}

- (void)application:(UIApplication *)application didReceiveRemoteNotification:(NSDictionary *)userInfo
    fetchCompletionHandler:(void (^)(UIBackgroundFetchResult))completionHandler {
  // If you are receiving a notification message while your app is in the background,
  // this callback will not be fired till the user taps on the notification launching the application.
  // TODO: Handle data of notification

  // With swizzling disabled you must let Messaging know about the message, for Analytics
  // [[FIRMessaging messaging] appDidReceiveMessage:userInfo];

  // Print message ID.
  if (userInfo[kGCMMessageIDKey]) {
    NSLog(@"Message ID: %@", userInfo[kGCMMessageIDKey]);
  }

  // Print full message.
  NSLog(@"%@", userInfo);

  completionHandler(UIBackgroundFetchResultNewData);
}
AppDelegate.m

Build send requests

After you have created a topic, either by subscribing client app instances to the topic on the client side or via the server API, you can send messages to the topic. In your sending logic on the backend, specify the desired topic name as shown:

Node.js

// The topic name can be optionally prefixed with "/topics/".
var topic = 'highScores';

var message = {
  data: {
    score: '850',
    time: '2:45'
  },
  topic: topic
};

// Send a message to devices subscribed to the provided topic.
admin.messaging().send(message)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });

Java

// The topic name can be optionally prefixed with "/topics/".
String topic = "highScores";

// See documentation on defining a message payload.
Message message = Message.builder()
    .putData("score", "850")
    .putData("time", "2:45")
    .setTopic(topic)
    .build();

// Send a message to the devices subscribed to the provided topic.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);
FirebaseMessagingSnippets.java

Python

# The topic name can be optionally prefixed with "/topics/".
topic = 'highScores'

# See documentation on defining a message payload.
message = messaging.Message(
    data={
        'score': '850',
        'time': '2:45',
    },
    topic=topic,
)

# Send a message to the devices subscribed to the provided topic.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)
cloud_messaging.py

Go

// The topic name can be optionally prefixed with "/topics/".
topic := "highScores"

// See documentation on defining a message payload.
message := &messaging.Message{
	Data: map[string]string{
		"score": "850",
		"time":  "2:45",
	},
	Topic: topic,
}

// Send a message to the devices subscribed to the provided topic.
response, err := client.Send(ctx, message)
if err != nil {
	log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)
messaging.go

C#

// The topic name can be optionally prefixed with "/topics/".
var topic = "highScores";

// See documentation on defining a message payload.
var message = new Message()
{
    Data = new Dictionary<string, string>()
    {
        { "score", "850" },
        { "time", "2:45" },
    },
    Topic = topic,
};

// Send a message to the devices subscribed to the provided topic.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);

REST

POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
  "message":{
    "topic" : "foo-bar",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message"
      }
   }
}

cURL command:

curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "message": {
    "topic" : "foo-bar",
    "notification": {
      "body": "This is a Firebase Cloud Messaging Topic Message!",
      "title": "FCM Message"
    }
  }
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

To send a message to a combination of topics, specify a condition, which is a boolean expression that specifies the target topics. For example, the following condition will send messages to devices that are subscribed to TopicA and either TopicB or TopicC:

"'TopicA' in topics && ('TopicB' in topics || 'TopicC' in topics)"

FCM first evaluates any conditions in parentheses, and then evaluates the expression from left to right. In the above expression, a user subscribed to any single topic does not receive the message. Likewise, a user who does not subscribe to TopicA does not receive the message. These combinations do receive it:

  • TopicA and TopicB
  • TopicA and TopicC

You can include up to five topics in your conditional expression.

To send to a condition:

Node.js

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
var condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
var message = {
  notification: {
    title: '$GOOG up 1.43% on the day',
    body: '$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.'
  },
  condition: condition
};

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
admin.messaging().send(message)
  .then((response) => {
    // Response is a message ID string.
    console.log('Successfully sent message:', response);
  })
  .catch((error) => {
    console.log('Error sending message:', error);
  });

Java

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
String condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
Message message = Message.builder()
    .setNotification(new Notification(
        "$GOOG up 1.43% on the day",
        "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day."))
    .setCondition(condition)
    .build();

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
String response = FirebaseMessaging.getInstance().send(message);
// Response is a message ID string.
System.out.println("Successfully sent message: " + response);
FirebaseMessagingSnippets.java

Python

# Define a condition which will send to devices which are subscribed
# to either the Google stock or the tech industry topics.
condition = "'stock-GOOG' in topics || 'industry-tech' in topics"

# See documentation on defining a message payload.
message = messaging.Message(
    notification=messaging.Notification(
        title='$GOOG up 1.43% on the day',
        body='$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.',
    ),
    condition=condition,
)

# Send a message to devices subscribed to the combination of topics
# specified by the provided condition.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)
cloud_messaging.py

Go

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
condition := "'stock-GOOG' in topics || 'industry-tech' in topics"

// See documentation on defining a message payload.
message := &messaging.Message{
	Data: map[string]string{
		"score": "850",
		"time":  "2:45",
	},
	Condition: condition,
}

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
response, err := client.Send(ctx, message)
if err != nil {
	log.Fatalln(err)
}
// Response is a message ID string.
fmt.Println("Successfully sent message:", response)
messaging.go

C#

// Define a condition which will send to devices which are subscribed
// to either the Google stock or the tech industry topics.
var condition = "'stock-GOOG' in topics || 'industry-tech' in topics";

// See documentation on defining a message payload.
var message = new Message()
{
    Notification = new Notification()
    {
        Title = "$GOOG up 1.43% on the day",
        Body = "$GOOG gained 11.80 points to close at 835.67, up 1.43% on the day.",
    },
    Condition = condition,
};

// Send a message to devices subscribed to the combination of topics
// specified by the provided condition.
string response = await FirebaseMessaging.DefaultInstance.SendAsync(message);
// Response is a message ID string.
Console.WriteLine("Successfully sent message: " + response);

REST

POST https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Content-Type: application/json
Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA
{
   "message":{
    "condition": "'dogs' in topics || 'cats' in topics",
    "notification" : {
      "body" : "This is a Firebase Cloud Messaging Topic Message!",
      "title" : "FCM Message",
    }
  }
}

cURL command:

curl -X POST -H "Authorization: Bearer ya29.ElqKBGN2Ri_Uz...HnS_uNreA" -H "Content-Type: application/json" -d '{
  "notification": {
    "title": "FCM Message",
    "body": "This is a Firebase Cloud Messaging Topic Message!",
  },
  "condition": "'dogs' in topics || 'cats' in topics"
}' https://fcm.googleapis.com/v1/projects/myproject-b5ae1/messages:send HTTP/1.1

Next steps