Please take a look at the iOS push payload at https://developer.apple.com/library/ios/documentation/NetworkingInternet/Conceptual/RemoteNotificationsPG/Chapters/TheNotificationPayload.html#//apple_ref/doc/uid/TP40008194-CH107-SW1
"category" is not supported in iOSAps when push.sendPayload(user,iOSAps, iOSExtras, androidPayload, callback).
The Kinvey Engineering has reviewed this enhancement request and has decided to include it as part of a number of Push Usability Improvements that Kinvey intends to development that will be available in the Q3/Q4 timeframe of 2016 (last half of this year) so it is now included in our Product Roadmap.
Please let us know if you have additional questions.
Sounds great. Thanks.
At present we do not have this capability, but I will turn this into a feature request and get back to you when I know more information.