Apple Feedback Service and Push Notification errors

Question

I have a server where I register device tokens that will be used to send push notifications via APNS.

I need to remove invalid device tokens from that server, and by reading Apple's documentation I've learned that there is a Feedback Service that will return de-registered device tokens which I can use to remove the entries on my server.

However I've seen that you also get errors when sending push notifications that weren't correctly delivered.

I found a table - table 5.1 - that contains some error codes that the response can have.

What is the difference between these error codes (specifically #8 - invalid token) and the devices that are returned in the FeedbackService?

From my understanding in the FeedbackService I can get device tokens for devices where my app was uninstalled. But can't I get the device token for a device where my app was uninstalled while trying to send a push notification to it (getting an error code 8)?

What kind of errors are only caught by the FeedbackService that I can't get via the push notification response?

Answer 1

If your app was uninstalled, but your server nerver send a push notification to it. Is that means that you nerver have the chance to remove those invalid token? What's more, when app was uninstalled, its push token will not available immediately。