Apple posted a note to developers this week saying that, soon, all new app updates in the iOS App Store must support both the iPhone X's display—that is, the notch and the phone's unique screen dimensions—and the iOS 11 SDK. The company will begin enforcing this rule in July.

This is the next phase in a series of announcements and changes from Apple to guide developers in supporting new hardware and software. In February, Apple said that all submissions of new apps must support these same features. In this case, it's not just new apps that have to comply: iOS 11 and iPhone X support will be required to submit updates for existing apps, too.

This is the developer update Apple posted:

iOS 11 delivers innovative features and the redesigned App Store to hundreds of millions of customers around the world. Your apps can deliver more intelligent, unified, and immersive experiences with Core ML, ARKit, new camera APIs, new SiriKit domains, Apple Music integration, drag and drop for iPad, and more. Starting July 2018, all iOS app updates submitted to the App Store must be built with the iOS 11 SDK and must support the Super Retina display of iPhone X.

After the iPhone X launched, Ars interviewed several iOS app and game developers to learn what is required to support the iPhone X. We learned that—as long as developers had already been following Apple's existing design guidelines rather than relying heavily on custom layouts—the transition is not usually difficult.

The TrueDepth sensor array housing—or the notch, as most have come to call it—was usually not the biggest challenge. Rather, developers told us that the main challenge is supporting the new almost-always-on-screen home indicator, which is a thin bar that indicates the user can swipe up to access multitasking and other features.

Apple has been providing developers with videos and documentation on how to support the new features for many months now. Many well-maintained, popular apps have already been updated, but there are plenty that still haven't.

Later this year, Apple is expected to launch more phones with similar screen shapes to that of the iPhone X, so support will be even more important. This is not the first time Apple has issued deadlines to support certain features; it has done so on similar schedules with prior iPhones.