Is it possible to detect Android app uninstall?

Question

My app is using Google's C2DM (push notification) to notify users about new activity from friends. Once they install the app I register the device with C2DM servers and store user's phone number. So I know that the user is using my app and I can send him/her the push notifications. But what happens if users uninstalls my app, is there a way to catch it in my app? Or the only way is to catch an error on my server when I send a C2DM and it's unreachable, then mark a user as inactive?

I would love to notify users when their friends are using an app and when they no longer do.

What's is the best solution for this scenario?

Answer 1

The GCM documentation explains this situation here:

https://developers.google.com/cloud-messaging/registration#how-uninstalled-client-app-unregistration-works

"An application can be automatically unregistered after it is uninstalled from the device. However, this process does not happens right away, as Android does not provide an uninstall callback."

Basically when GCM tries to send the next push notification, the device will tell GCM the receiving application was uninstalled.

As for notifying friends that their friends aren't using the app any more, GCM will send a NotRegistered error to your notification server when this failure occurs; it won't be immediate, but could you use that?