And then there’s SwiftUI, which may be a harder concept for regular users to grasp, but it’s a huge step on Apple’s part. This is Apple’s ultimate long game—an entirely new way to design and build apps across all of Apple’s platforms, based on the Swift language (introduced five years ago as yet another part of Apple’s long game).
In the shorter term, iOS app developers will be able to reach to the Mac via Catalyst. But in the longer term, Apple is creating a new, unified development approach to all of Apple’s devices, based in Swift and SwiftUI. Viewed from this perspective, Catalyst feels more like a transitional technology than the future of Apple’s platforms.
Apple’s own SwiftUI page provides more details. This is the future of application development across all of Apple’s platforms, so if you have a vested interested in the Apple world, you’d do good to get yourself acquainted with it.