What is the impact of the "Requires full screen" option in Xcode for an iPhone-only app?

Solution 1:

There is no impact at all. Apple engineers thinks that its not required to hide, or may be Plus phones will get landscape slide over in later iOS versions :)

From the documentation:

To opt out of being eligible to participate in Slide Over and Split View, add the UIRequiresFullScreen key to your Xcode project’s Info.plist file and apply the Boolean value YES.

Solution 2:

Normally, you would need to support both portrait and landscape orientation in your app.If your app is landscape only or portrait only, then the app validation fails with:

warning: All interface orientations must be supported unless the app requires full screen.

And as KingofBliss noted, setting this to YES will also stop your app from running in a split view.

It is a useful setting for games that run full screen in landscape only.