How new GCM handles APNS feedback?

Question

I was trying out new GCM feature to send notifications to iOS devices. Everything worked very smooth except the feedback message. I assume after GCM sends message through APNS, GCM also calls feedback service of APNS to get the invalid tokens. Next time when we use the same device token to GCM, it should respond with error message. I tried several times after uninstalling the app, but never received an error message from GCM. Each time it shows success message. What went wrong here?

Note: If you are not familiar with new GCM features, please do not blindly answer to this.

Answer 1

I think the problem here is with the environment. I am using developer certificate to test the notification. APNS may not be giving any details for developer environment. Hope it will work in production.

Updates

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Support from Google gave following details.

We did some digging, it seems that is how things are being handled by APNS:

• When last sandbox app is removed from the device, device disconnects from APNS sandbox and not able to receive pushes/provide feedback anymore. Thus, APNS feedback doesn't register that the device has been uninstalled.
• If you install another push-enabled sandbox app on the device, which would force device connection to APNS again. And we checked that under this circumstance, we get notified that the device has been uninstalled and return NotRegistered to our client.