Indicate if subscribe/unsubscribe to topic failed

[svenboogaarthotraco]

Documentation issue

What happens when the methods do not work.
E.g. if subscribe fails how can one detect it, as the return type is void according to https://github.com/dpa99c/cordova-plugin-firebasex/blob/master/types/index.d.ts#L55

[dpa99c]

These functions are directly inherited from cordova-plugin-firebase.

Looking at the source code, neither Android or iOS returns a result for subscribe/unsubscribe actions.

However, looking at the Firebase documentation, it looks like subscribeToTopic on Android returns a Task object which should indicate a success/failed state, and on iOS it should be possible to change from using subscribeToTopic: to subscribeToTopic:completion: which also indicates if an error occurred.

The same should be possible for unsubscribe actions.

So rather than being a documentation issue, this is a legacy code issue in that it doesn't actually indicate whether there was an error in subscribing/unsubscribing to a topic.

I'll change the issue to reflect this.

[svenboogaarthotraco]

@dpa99c Is there another way I can check if subscribe if succesffull, e.g. is it possible to get my subscribtions? If thats possible I can validate if the expected subscribe is succesfull. Is it correct there is a few minutes delay between subscribe and when you can actually receive the messages? When testing in an android emulator it takes a few minutes before I can actually send messages to a subscribed device. PS, is there a forum or something where I should ask question. I have the feeling i should not post it under issues.

[Hao-Axon]

@dpa99c I get "Task failed for unknown reason" error from .subscribe now. But seems like the subscribe is actually successful and the app can receive messages after the error.