Talking about Apple. Notice that in the comments section of this article, there's nobody even mentioning Ultraflix being available on IOS for 4k streaming, although some complain about the lack of 4k content. Still, it was a big issue here some time ago.
http://9to5mac.com/2015/09/02/apple-tv-4-2015-specs/
Strange that those Mac guys don't know by now about Ultraflix being on Apple.