Introduced in back in September, the iOS 11 SDK includes new technologies for app developers like Core ML, ARKit, revamped camera APIs, additional SiriKit domains, drag and drop features for the iPad, and more.
Going forward, iOS apps will need to adopt these technologies, and more importantly, Apple will be forcing developers who have not yet implemented support for the new display of the iPhone X to do so. While most major apps have added support for the iPhone X, there are still many apps that have not been updated and continue to have ugly black bars when used on the iPhone X.
This includes some Apple apps, such as iTunes Connect, iTunes Remote, Beats Pill+, Music Memos, and AirPort Utility, so presumably Apple will be updating its own apps with full iPhone X support in the near future given the new guidelines.
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.Apple's requirement for app updates to introduce iPhone X support will be implemented just a few months ahead of the launch of new 2018 iPhones that will be similar in design to the existing iPhone X. Apple is rumored to be working on three phones: a 5.8-inch OLED device that's a successor to the iPhone X, a 6.5-inch OLED device that can be thought of as a sort of "iPhone X Plus," and a 6.1-inch LCD iPhone that will have a lower price tag.
Apple in April began requiring all new apps to be built with the iOS 11 SDK and with support for the iPhone X's display.