[crashlytics] add method to specify firebase app

[wferem1]

What feature would you like to see?

Add FirebaseCrashlytics instance(FirebaseApp app) method, so that not the default application is used.

How would you use it?

We have a firebase project for each backend stage in our application. Since we are dealing with sensitive user data, not everyone can just look at all the projects. We want to sent crashlytics to a specific firebase project, depending on which stage of the backend the user select. But currently only the default application is used.

Since we're building a flutter application, this also have to be implemented in the ios SDK and the flutterfire/firebase_crashlytics plugin. (see also firebase/flutterfire#9109).

[google-oss-bot]

I couldn't figure out how to label this issue, so I've labeled it for a human to triage. Hang tight.

[argzdev]

Thanks for filing, @wferem1. Our engineers will take a look into it once they have the time. While we can't promise any timeline for this feature, if others find this useful adding an emoji thumbs up on the original post can help our engineers prioritize adding this to the roadmap.

Alternatively, you could try the solution provided on #187, since these seems like a similar use case.

[wferem1]

Thanks @argzdev , however the solution in #187 is not sufficient, since we want to change the when the app is already running, and another crashlytics instance was already initialized. This would mean we have to overwrite the default application, which is not possible in the current implementation.

[argzdev]

I see, that makes sense. Thanks for explaining, @wferem1.