iOS critical alert through FCM

Question

iOS 12 has added critical alerts. The APNS payload has the sound dictionary to support critical alerts. Is there an equivalent sound dictionary support in FCM payload to send FCM notifications to iOS devices.

Answer 1

Critical alerts have now been added by firebase.

It can be added to the MessagingPayload like this:

const messagingPayload = {
  token: this.FCMToken,
  notification: {
    ...payload,
  },
  apns: {
    payload: {
      aps: {
        criticalSound: {
          critical: true,
          name: 'default',
          volume: 1.0,
        },
      },
    },
  },
};

return admin.messaging().send(messagingPayload);

The docs can be a little confusing. You have to use messaging().send() and encode the token in the payload, instead of using messaging().sendToDevice().

The payload message is a TokenMessage https://firebase.google.com/docs/reference/admin/node/admin.messaging.TokenMessage

p.s.

You also need to get an entitlement from Apple before you can use critical alerts: https://developer.apple.com/contact/request/notifications-critical-alerts-entitlement/

Answer 2

Answering my own question.

I had to rely on notification extension to do the magic as the FCM payload doesn't support the iOS sound dictionary. I send the "critical" flag set to 1 as part of FCM data payload and use it in notification extension to mark a notification as critical.

class NotificationService: UNNotificationServiceExtension {
    var contentHandler: ((UNNotificationContent) -> Void)?
    var bestAttemptContent: UNMutableNotificationContent?

    override func didReceive(_ request: UNNotificationRequest, withContentHandler contentHandler: @escaping (UNNotificationContent) -> Void) {
       self.contentHandler = contentHandler
       bestAttemptContent = (request.content.mutableCopy() as? UNMutableNotificationContent)
       let userInfo: [AnyHashable : Any] = (bestAttemptContent?.userInfo)!
       if let apsInfo = userInfo["aps"] as? [AnyHashable: Any], let bestAttemptContent = bestAttemptContent, let critical =  userInfo["critical"] as? String, Int(critical)! == 1 {
            //critical alert try to change the sound if sound file is sent in notificaiton.
            if let sound = apsInfo["sound"] as? String {
                //sound file is present in notification. use it for critical alert..
                bestAttemptContent.sound =
                    UNNotificationSound.criticalSoundNamed(UNNotificationSoundName.init(sound),
                                                           withAudioVolume: 1.0)
            } else {
                //sound file not present in notifiation. use the default sound.
                bestAttemptContent.sound =
                                UNNotificationSound.defaultCriticalSound(withAudioVolume: 1.0)
            }
            contentHandler(bestAttemptContent)
        }
    }
}

Answer 3

There is currently no sound dictionary support in FCM which is equivalent to iOS' sound dictionary. As I'm sure you're already aware of, the counterpart of FCM with APNs' when it comes to sound is the sound parameter:

The sound to play when the device receives the notification.

Sound files can be in the main bundle of the client app or in the Library/Sounds folder of the app's data container. See the iOS Developer Library for more information.

However, reading from the UNNotificationSound docs, maybe you could try adding a data message payload that contains an identifier (e.g. "isCritical": "true") then have your app handle it as needed.

Answer 4

Using new api is possible:

import firebase_admin
from firebase_admin import credentials
from firebase_admin import messaging

#for generate credential use this tutorial: https://medium.com/@ThatJenPerson/authenticating-firebase-cloud-messaging-http-v1-api-requests-e9af3e0827b8
cred = credentials.Certificate("/dir-your-credential/credentical.json")
firebase_admin.initialize_app(cred)


# This registration token comes from the client FCM SDKs.
registration_token = 'example-YynJsQ96UFvhER7mBeYD6'

# See documentation on defining a message payload.
message = messaging.Message(
    notification=messaging.Notification(
      body = 'Hi body message \uD83D\uDEA9',
      title = 'Title Push'
     ),
    apns=messaging.APNSConfig(
        payload=messaging.APNSPayload(
            aps=messaging.Aps(badge=2, sound=messaging.CriticalSound(critical=True, name="your-song-alert.wav", volume=0.8)),
        ),
    ),
    token=registration_token,
)

# Send a message to the device corresponding to the provided
# registration token.
response = messaging.send(message)
# Response is a message ID string.
print('Successfully sent message:', response)