Use iPhone as a game controller in a tvOS app?

Question

During the Apple TV announcement, the developers of Crossy Road demonstrated using an iPhone as a 2nd controller for an Apple tv game:

http://www.macrumors.com/2015/

Answer 1

Well, I'm not sure it qualifies as a "good way", but GKMatchRequest and GKMatchmaker are in there, so maybe that's what they're using.

https://developer.apple.com/library/prerelease/tvos/documentation/GameKit/Reference/GKMatchRequest_Ref/