Last year Steam announced the software version of Steam Link for Android and iOS. It would allow you to stream games to your smart device while your PC is the one doing the hard work.
The Android launch went smoothly, but Apple rejected the app. Valve commented on this and said that it was due to “business conflicts”.
Apple clarified that they don’t allow apps to offer app-like purchasing stores, but apps that offer remote desktop connections that allow purchases through the desktop version of the app are acceptable. Valve removed the ability to buy games through the Steam Link app and submitted it for approval again.
Finally, the app has been approved and you are able to stream your entire Steam library on your iPhone or iPad. Just remember that a stable internet connection is needed. It is recommended that your PC has a wired connection and to not move your iOS device far from the router.