A few months ago, Mark Gurman reported that Apple was working on a way to enable developers to write applications that run on both macOS and iOS. I briefly mentioned it on this blog. Now John Gruber at Daring Fireball reports more details:
THE NAME: There is indeed an active cross-platform UI project at Apple for iOS and MacOS. It may have been codenamed “Marzipan” at one point, but if so only in its earliest days. My various little birdies only know of the project under a different name, which hasn’t leaked publicly yet. […]
WHAT IS IT? I don’t have extensive details, but basically it sounds like a declarative control API. The general idea is that rather than writing classic procedural code to, say, make a button, then configure the button, then position the button inside a view, you instead declare the button and its attributes using some other form. HTML is probably the most easily understood example. […]
WHEN: I’m nearly certain this project is not debuting at WWDC 2018 in June, and I doubt that 2018 was on the table in December. It’s a 2019 thing, for MacOS 10.15 and iOS 13.
What these technologies allow developers to do is separate the user interface from the code that runs it. The user interface becomes a matter of declaring, using a relatively simple text-based syntax, that the developer wants a button here or a text label there, etc. Separately, then, the developer defines what should happen when that button gets clicked. ↩