All new apps and app updates must support the iPhone XS Max and latest 12.9-inch iPad Pro starting March 27.
In a post on its developer portal, Apple notes that apps must be built with the iOS 12.1 SDK or later. New Apple Watch apps must also support the Apple Watch Series 4.
While older apps will continue to run, they will not be optimized for the latest devices. As Apple points out in its note, iOS 12 is now running on upward of 80 percent of devices worldwide.
In addition to optimizing apps for its latest slew of devices, developers must also include screenshots for these devices.
Memory usage challenges
As Apple writes, iOS 12 developing differs slightly from previous iOS versions. Specifically, it requires that developers use memory “far more efficiently” than in past versions. To help devs to reduce app memory requirements, it offers guidance in the form of help pages.
Developers unable to reduce memory requirements can also contact Apple to request an entitlement for your app to use iOS 11-style memory accounting. This also goes for tvOS 12, the latest version of the Apple TV operating system.