问题
Apple push notification - Feedback Service
How do you know when the user uninstalls your application? so that you can remove their devicetoken from the push server.
回答1:
You simply don't know. You can grab device identification string which is presumably identical for the same application token string, and track if a token has changed for the specific device. So you can update the device token with a new one, but there is no way to find out if your app was removed from a device.
Update: You are correct. You can get this information from the feedback service, however there is a caveat. You need to have at least one push-messaging enabled application installed to maintain persistent feedback connection. I'd mark these customers as potentially non-existant, but I wouldn't remove these folks from a customer DB. Who knows why your push message can be rejected. Your device may be in inconsistent state and you remove your subscriber forever. If you have 10k zombie clients it is a pocket change for a DB. If you lost 100k clients you have much serious problems than that.
来源：https://stackoverflow.com/questions/5100343/push-notification-feedback-uninstall-application