Hi @adityathoutam

Thank you for reporting the issue. Yes, I can reproduce the issue with quickstart on iOS as well.

Based on the Firebase iOS SDK doc, seems like there are several extra steps in Xcode to make it works, ex. Notification Service Extension.

The Xcode project generated from Unity is slightly complicated since it has two different targets, UnityFramework and Unity-iPhone. I am not sure if those steps from iOS SDK doc is valid. Will need to consult with our iOS team.

@adityathoutam As @chkuang-g mentioned, setup Notification service extension is a required step and you need to call the Messaging ExtensionHelper API inside the extension.
Here's a tutorial you can check out: https://firebase.google.com/docs/cloud-messaging/ios/send-image
Let us know if you already done that and it still doesn't work for you.

@chliangGoogle As @chkuang-g mentioned, Unity creates two different targets UnityFramework and Unity-iPhone.
There are no instructions on what to do in this case. I have added the Notification service extension but I think it is not aware of the Firebase Messaging inside Unity. I have tried adding Firebase as pods dependencies, but Xcode is showing me 99 errors. Here is the pod file
`source 'https://github.com/CocoaPods/Specs.git'
platform :ios, '11.0'

def shared_pods
pod 'AppsFlyerFramework', '6.0.7'
pod 'Firebase/Analytics', '7.0.0'
pod 'Firebase/Auth', '7.0.0'
pod 'Firebase/Core', '7.0.0'
pod 'Firebase/Crashlytics', '7.0.0'
pod 'Firebase/Database', '7.0.0'
pod 'Firebase/Functions', '7.0.0'
pod 'Firebase/Messaging', '7.0.0'
pod 'Firebase/RemoteConfig', '7.0.0'
pod 'Firebase/Storage', '7.0.0'
pod 'PurchasesHybridCommon', '1.4.5'
end

target 'UnityFramework' do
shared_pods
end

target 'Unity-iPhone' do
target 'NotificationImage' do
shared_pods
end
end`

@chkuang-g can you try it in unity and see if this is reproducible.

In regular iOS app, the Messaging needs to be installed inside service extension as well: https://github.com/firebase/firebase-ios-sdk/blob/master/FirebaseMessaging/Apps/AdvancedSample/Podfile

@chkuang-g will test on unity to see if it's the similar case.

Yes, I noticed that Unity generates multiple targets and has UnityFramework embedded in Unity-iPhone.

I have not try to set it up yet but I think that should be align with this sample.

https://github.com/firebase/firebase-ios-sdk/tree/master/FirebaseMessaging/Apps/AdvancedSample

Will keep you updated.

Alright, finally had a chance to crack this.

Here are all the steps you need to make it work. This has been tested with our quickstart project.

1. (Optional) Install Firebase 7.1.0. It includes a couple of fixes for Podfiles and Xcode project which should make the following steps much easier. See iOS App Crash ( podFile to use_frameworks! Issue when used ) #862

2. Follow all of the steps from our sample readme.

3. Follow this doc to add Notification Service Extension to your Xcode project and modify NotificationService.m (or NotificationService.swift, if you prefer Swift ). Make sure you sort out the provision profile for this new target as well.

   When you have doubt, try to reference this iOS sample and see the difference in your Xcode project (Remember to copy your GoogleServices-Info.plist to your AppClips folder and change bundle id that match your Firebase project and your provision profile).

4. Modify Podfile in your Xcode project. The basic idea here is you need Firebase/Messaging pod for both UnityFramework target and your new Notification Service Extension target (NotificationImage for your case, I assume). Your Podfile should look like the following

   source 'https://github.com/CocoaPods/Specs.git'
   platform :ios, '11.0'
   
   target 'UnityFramework' do
     pod 'Firebase/Core', '7.5.0'
     pod 'Firebase/Messaging', '7.5.0'
   end
   target 'Unity-iPhone' do
   end
   # This should use the name of your Notification Service Extension
   target 'NotificationServiceExtension' do
     pod 'Firebase/Messaging', '7.5.0'
   end
   use_frameworks!
   # Use the following if you do not have other Swift framework pods for stability
   #  use_frameworks! :linkage => :static
   

   NOTE that I found that Xcode in general does not like to have the same pod added to multiple targets without use_frameworks!. This can be the reason of your complier error.
   Learn more about the nuisance in this thread iOS App Crash ( podFile to use_frameworks! Issue when used ) #862

5. Run pod install under your Xcode project to regenerate Unity-iPhone.xcworkspace.

And that's it. Should be working by now.

I can see several issues here.

• It is tedious.
• When you regenerate Xcode project, even incrementally, External Dependency Manager for Unity will override Podfile you modified for good, which can be extremely annoying. One possible workaround to alleviate the pain for now is to add a script like this iOS App Crash ( podFile to use_frameworks! Issue when used ) #862 (comment) to add the NotificationServiceExtension section automatically.
• I did notice a different behavior between iOS sample and quickstart-unity. For iOS sample, the notification show up in the notification tray no matter the app is foreground, background or killed. And for quickstart-unity, the notification is only in notification tray IF the app is in the background or killed. This seems to be an inconsistent behavior.

Let me know if this helps. At the meantime, I will change this to a feature request for all the frictions I described above (maybe a bug for the last one).

Shawn