Apple announced a new provider API for APNs based on HTTP/2 at WWDC 2015. Currently, there is no written documentation, but it should be available in the coming weeks.
See this video starting at 20:50 for an introduction to the new API: https://developer.apple.com/videos/wwdc/2015/?id=720
Also see the slides starting at page 98: http://devstreaming.apple.com/videos/wwdc/2015/720xwbi9nl/720/720_whats_new_in_notifications.pdf?dl=1