Flutter - Background notifications not working in iOS - firebase

Question

I'm creating a public chat app in Flutter, and I can't receive background notifications on iOS, when I trigger the method admin.messaging().send(payload) from my Cloud Function.
Here's my payload in the Cloud Function :
var payload = {
notification: {
title: `My Title`,
body: `My message`,
},
android: { priority: "high" },
apns: {
payload: {
aps: {
contentAvailable: true,
},
},
headers: {
"apns-push-type": "background",
"apns-priority": "10",
"apns-topic": "io.flutter.plugins.firebase.messaging", // bundle identifier
},
},
topic: `mytopic`,
};
I tried a bunch of different payloads :
I tried notification + data
I tried only data (no notification) (in that case, I have to locally display the notification, but it is not working because the function FirebaseMessaging.onBackgroundMessage is never called)
I tried to change "apns-priority" to 5
I tried using a token instead of a topic
I set up carefully all I need to configure, thanks to the official documentation :
https://firebase.flutter.dev/docs/messaging/usage/
I also checked Github issues, like these ones :
1041, 6112, 5988, 1644, 4300, 4097
What is working :
Background and foreground notifications on Android and iOS, when sent from Firebase Console (in 'Cloud Messaging' section)
Background and foreground notifications on Android only, when sent from Cloud Function
Foreground notifications on iOS, when sent from Cloud Function
What is NOT working :
Background notifications on iOS when sent from Cloud Function
When app is terminated, it does not work as well.

Answer 1

I finally resolved this issue ! 🎉
I simply removed the line "apns-push-type": "background" in my payload.
Now it is working.
It appears that the line "apns-topic" was useless as well.
Here is my final payload :
var payload = {
notification: {
title: `# ${context.params.passion}`,
body: `${newMsg["senderPseudo"]} ${
type == "image" ? "a envoyé une image." : `: ${newMsg["message"]}`
}`,
},
// Set Android priority to "high"
android: {
priority: "high",
},
// Add APNS (Apple) config
apns: {
payload: {
aps: {
contentAvailable: true,
},
},
headers: {
//"apns-push-type": "background", // This line prevents background notifications to be displayed
"apns-priority": "10",
},
},
token: "dnqTQVso60GfnnuOjHv8_e:APA91bElr-K3xkQMdYHX8VMrMZNCYCjO4zJlGseRh25AS_GT7cg9zlOGdQl4KXvr88ypeWjZjrPzrLRHitsQ-JKQK057ZQb_36c_lfsNjHXbYMYI2iS3jV_HGWf7Ene-ZlPvOb0aRr8u"
};