FCM iOS: Push notifications throw invalid argument - node.js

Question

I am attempting to implement pushNotifications using Cloud Functions and FCM for iOS but I am consistently thrown this error:
2018-05-21T13:04:00.087Z I sendPushNotifications: Error sending
message: { Error: Request contains an invalid argument.
at FirebaseMessagingError.Error (native)
at FirebaseMessagingError.FirebaseError [as constructor] (/user_code/node_modules/firebase-admin/lib/utils/error.js:39:28)
at FirebaseMessagingError.PrefixedFirebaseError [as constructor] (/user_code/node_modules/firebase-admin/lib/utils/error.js:85:28)
at new FirebaseMessagingError (/user_code/node_modules/firebase-admin/lib/utils/error.js:241:16)
at Function.FirebaseMessagingError.fromServerError (/user_code/node_modules/firebase-admin/lib/utils/error.js:271:16)
at /user_code/node_modules/firebase-admin/lib/messaging/messaging-api-request.js:149:50
at process._tickDomainCallback (internal/process/next_tick.js:135:7) errorInfo: { code:
'messaging/invalid-argument',
message: 'Request contains an invalid argument.' }, codePrefix: 'messaging' }
My implementation in cloud functions are as follows:
exports.sendPushNotifications = functions.database.ref('/conversations/{userUid}/').onWrite((snap, context) => {
const userUid = context.params.userUid
console.log("Triggered user ", userUid)
return admin.database().ref('/fcmToken/' + userUid).once('value', snapshot => {
const values = snapshot.val()
const fcmToken = values.fcmToken
var message = {
"token": fcmToken,
"notification": {
"body": "New message"
},
"apns": {
"headers": {
"apns-priority": "5"
},
"payload": {
"aps": {
"alert": {
"body": "New message"
},
"badge": "1",
"sound": "default"
}
}
}
};
return admin.messaging().send(message)
.then((response) => {
return console.log('Successfully sent message:', response);
})
.catch((error) => {
return console.log('Error sending message:', error);
});
})
})
The frustrating thing is that when I remove the whole "apns" node the code actually works, ie I can receive the push notifications. I suppose this means my setup are all done properly. Once I included the "apns", it starts throwing the above error. I also reference these three posts, this, this and this, and made sure that I have carefully followed the code and instructions. For some reasons I cannot get it to work.
I also attempted to remove the "notification" node as the docs did mention that only use common keys when targetting all platforms. Since I am targetting only iOS for now, I suppose I should remove the "notification" key. But again it also throws the same error.

Answer 1

Ok, so it was a rookie mistake. It is correct that common keys should not be used if I am targetting iOS only. In addition to that, the badge should be an Int and not String.
This code worked:
var message = {
"token": fcmToken,
"apns": {
"headers": {
"apns-priority": "5"
},
"payload": {
"aps": {
"alert": {
"body": "New message"
},
"badge": 1,
"sound": "default"
}
}
}
}
Hope it helps anyone out there facing the same problem.

Answer 2

Just to add to this answer. If you are using both IOS and android while having custom sounds for both, the code below will work cross platform and avoid this issue.
const payload = {
token,
notification: {
title: `title text`,
body: `body text`,
},
android: {
// android
priority: "high", // legacy HTTP protocol (this can also be set to 10)
notification: {
channel_id: "call1",
priority: "high", // HTTP v1 protocol
notification_priority: "PRIORITY_MAX",
sound: "sound",
default_sound: true,
visibility: "PUBLIC",
},
},
apns: {
// apple
headers: { "apns-priority": "10" },
payload: {
aps: {
// If present with notification: {...}, this will create errors
// "alert": {
// "title": `title text`,
// "body": `body text`,
// },
badge: 1,
sound: {
critical: 1,
name: "sound.aiff",
volume: 1,
},
category: "call1",
},
},
},