Source: Microsoft
After bringing the feature to Android, we get confirmation that Microsoft is testing Xbox remote play on iOS, too. As you expect, the app connects to your Xbox One (or one of the upcoming consoles) and lets you play the games already available on your system. It isn't like Microsoft's xCloud service, which will run games from the cloud. Sony has something similar with its Remote Play app.
According to The Verge's Tom Warren, the beta app looks stable, and it should arrive on the App Store soon. But Microsoft isn't saying when it'll be available.