This Backbone iPhone controller is your best option for xCloud

[Windows Central]

The Backbone One is the best gamepads for iPhone, but with clever use of iOS features, it doubles as a slick gaming platform you won't find elsewhere.
The rise of cloud gaming has driven a new era of mobile gaming accessories for smartphones, many imitating dedicated handheld consoles, albeit some more viable than others. The Backbone One is among the latest breaking into the space, and with Microsoft expanding its game-streaming tech to iOS, there's a compelling basis for its $99 asking price to Xbox owners.

Full story from the WindowsCentral blog...