问题
When Googleing for ios device token expiration topic you'll find many notices about Apple Feedback Service. It's for polling of device token expiration so when Feedback Service told that particular device token is expired it means that there is no chance to deliver push-notification to that device token. We should mark them as expired.
Now I couldn't find any Feedback Service mention in actual Apple docs.
Is this service deprecated? If so, why PushSharp, pushd libraries still use it? And if so, what to do next? Read send status as on Google and Microsoft platforms?
来源：https://stackoverflow.com/questions/34659089/apns-feedback-service-is-it-still-alive