问题
Example scenario:
I'm sending message to several devices using GCM. The response contains "multicast_id"? How can I use this value?
Thanks.
回答1:
It's just an identifier.
multicast_id Unique ID (number) identifying the multicast message.
There is no use for that ID, unless you wish to save it in your DB as a kind of "receipt" from Google, but the individual message_ids returned for each message that wasn't rejected by Google are much better as a receipt (since they indicate Google actually accepted your message and will try to deliver it).
来源：https://stackoverflow.com/questions/24853794/what-is-multicast-id-in-gcm-response