I saw one reference to limits on silent push notifications: "Silent pushes are rate limited—a handful per hour"
(From WWDC 2013: http://devstreaming.apple.com/videos/wwdc/2013/204xex2xvpdncz9kdb17lmfooh/204/204.pdf )
I haven't seen this documented anywhere else, and in our experiments we have not seen any such limit. Does anyone know if this is something we need to take into account? All descriptions of regular APNs seem to imply that there is no limit, and while they are not necessarily received in real time, they should eventually be delivered.
We are looking into using silent notifications as often as once a minute per device, so while not hammering the device every few seconds, certainly more than a few per hour.