Apple has a problem. Developers are making millions of apps for iPhone and iPad but only a small fraction of those ever come to the Mac. And that includes apps made by Apple itself. Likewise, Apple has teams working on its apps that increasingly have to develop and maintain features across iOS and macOS. Sometimes that causes work to go more slowly than anybody would like. Sometimes it causes a lack of feature parity that nobody likes.
So, what to do? The answer is bringing parts of UIKit, the iOS app framework, to macOS. That way, iOS-style apps can be deployed more quickly and easily to the Mac, and live alongside traditional AppKit apps, web-based apps, OpenGL games, and more.
What's new with Apple's universal framework (AKA: Marzipan)?
June 4, 2018: Apple announces iOS apps coming to the Mac in 2019, 'sneak peak' available in iOS 12 and macOS Mojave
At WWDC 2018, Apple announced that, no, it's not merging iOS and macOS, but yes, there a project underway to bring UIKit apps to the Mac. That means developers with iPhone and especially iPad apps can more quickly and easily port those apps to macOS.
Apple is testing how this universal framwork works in phases. With Phase 1, Apple is bringing the News app, Voice Memos app, Stocks app, and Home app to the Mac. These new Mac apps are literally just a port of the iPad versions. With Phase 2, developers will be able to start porting and deploying iOS apps of their own to the Mac.
April 30, 2018: 'Marzipan' isn't 'Marzipan', but it's coming 2019... as part of a new UI
John Gruber, writing for Daring Fireball:
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.
I just assumed Marzipan was the name for one of the candidates for this project, but that Apple was going ahead with a different candidate. Apple often weighs different approaches, like using AppKit or WebKit for iOS before coming up with UIKit, or other languages or storage technologies before going all-in on Swift or APFS.
I don't have extensive details, but basically it sounds like a declarative control API.
It could be part of a bigger project that, to borrow John's HTML analogy, brings a little CSS to the table?
It's a 2019 thing, for MacOS 10.15 and iOS 13.1 I would set your expectations accordingly for this year's WWDC.
That's also when the new Home screen and interface design are currently scheduled to appear, which John doesn't think is a coincidence. And is probably not a coincidence.
Wait, why would Apple need a cross-platform developer framework?
Currently, iOS apps use the UIKit frameworks and Mac apps use the older App Kit frameworks. Photos, which launched cross-platform, was implemented using the seemingly one-off UXKit for Mac, and wasn't exactly an ideal execution.
Other companies were using web apps, Electron (Chrome packaged web apps), or progressive web apps to deploy cross-platform. But, like the Java and AIR apps before them, the ease they offered developers was paid for by users who had to put up with a worse experience.
So, something that let iOS developers take their apps to the Mac, with robust Mac user interface support, seemed like the best solution. A new XKit that superseded UIKit and AppKit on both platforms.
It's such an obvious need, it came up in an early episode of my VECTOR podcast with Gui Rambo. We discussed the possibility of Apple making it easier for iOS developers to deploy apps on the Mac. Not just inside the company, but for everyone.
Just look at the incredibly popular iMessage and Safari, and the incredibly useful Notes and Maps. The ones with the most features have the least parity.
What does this universal framework mean for iOS and the Mac?
That's a complicated question, and triggers a lot of fears and uncertainties about how Apple sees the future of the Mac. To try and get a balanced view, I also asked Christina Warren, formerly of Mashable and Gizmodo, currently at Microsoft (which has been working on Universal Windows Apps), John Gruber of Daring Fireball, Loren Brichter, formerly of Tweetie (who made his own cross-platform framework, TWUI), Craig Hockenberry of Twitterrific (which once used a custom cross-platform framework, Chameleon), Ben Sandofsky of Halide, and Greg Pierce of Drafts, what they thought:
Opinions ranged for Marzipan being something Apple absolutely had to do, both for itself and for the developer community, to concerns over how it would be implemented and whether it would really benefit the Mac or just lead to the further atrophy of the platform.
When will Apple release this universal framework?
For developers, as soon as WWDC 2019 next June. It will come to iOS 12 and macOS Mojave for us in the fall of 2019 in the form of four Apple built apps that are being ported from iOS to Mac.
- Voice Memos
These apps are going to be identical to their mobile counterparts, but available on Mac! Once Apple feels confident that this testing phase is successful, we'll probably see a developer update.