https://www.gamespot.com/articles/valves-new-steam-link-app-blocked-by-apple-from-io/1100-6459206/

The cool new Steam Link app Valve announced recently, which allows you to stream Steam games to your mobile device, will apparently be an Android exclusive, at least for the time being. Following its recent announcement and subsequent beta release on Android, Valve has revealed that Apple has reversed its decision and will not allow the app to be released on the iOS App Store.