Apple Project Catalyst brings iPad apps to the Mac: What you need to know

As expected, Apple announced Project Catalyst Monday at WWDC, its annual developer conference. Project Catalyst -- previously referred to as Marzipan -- is a piece of software that Apple's been working on that will make it possible to install and use your favorite iPad apps on your Mac. 

This is an instantly appealing idea because it means that instead of installing duplicate apps on your iPad and on your Mac, you can download the same across multiple devices. Project Catalyst is in the same spirit as iMessage and Apple's notes app, which sync between your iPhone and your computer.

While this was announced today, you'll have to wait a little longer to take advantage of the new feature. Let's take a look at what Project Catalyst is exactly, timing and why you should even care.

What is Project Catalyst?

Project Catalyst is what Apple is calling the company's initiative to bring apps developed for the iPad to the Mac. Previous reports had referred to it as Project Marzipan, however, the public-facing name is now Project Catalyst. 

We got our first look at Catalyst apps when MacOS Mojave launched with the addition of Apple News, Stocks, Voice Memos and Home.

Prior to Catalyst, it wasn't for iOS apps to run on a Mac (or vice versa) due to differences in the underlying frameworks -- or software code required for apps to work on a platform. Up until now, iOS has relied solely on UIKit, while MacOS has used AppKit.

With Catalyst, Apple is adding elements of UIKit to MacOS, making it possible for an iOS app to run on a Mac.

Think of it as universal apps... on steroids

When a developer builds an app for Mac using Catalyst, they can check a box in the development program Xcode and it will build the Mac version of the app on the developer's behalf. The app can then be tweaked and customized to improve the experience on the Mac, but for the most part, all of the heavy lifting of converting an iOS app for MacOS has been done by Xcode. 

In a sense, Project Catalyst apps are Universal apps on steroids. If Universal Apps sounds familiar, it's because that's what Apple has called apps built for iPhone and iPad since the release of the iPad. 

Apple showed off a screenshot of Twitter's upcoming Catalyst-built app for MacOS, which is expected to be released alongside MacOS Catalina.

Wait, don't we already have Universal Apple apps?

Yes, but those apps are limited to the iPhone and iPad right now. We do have features like Continuity for using your iPhone to place phone calls on your Mac, or sharing clipboard contents between your iPad and Macbook . Looking back, it becomes clear features such as hand-off (for things like opening an email you're viewing on your iPad on your Mac) have been precursors to true universal apps in Apple's ecosystem.

iPhone-only apps need not apply

Apps built specifically for the iPhone without an iPad equivalent won't work with Project Catalyst. It's a decision that makes sense, given the layout differences when you compare an iPhone and iPad app. One is built in as a vertical, single column, while the other has multiple areas of information always on display -- just like a Mac app.

When will more iOS apps come to the Mac?

At Apple's WWDC conference last year, the company announced that iOS apps coming to the Mac would roll out in two phases. The first was the release of Apple's own apps on MacOS. Then Apple promised the second phase would give developers the tools to begin porting their iOS apps to MacOS in 2019.

Project Catalyst is built into MacOS 10.15 Catalina. Catalina is available to developers in beta right now, but won't officially launch until this fall.

Even when MacOS Catalina is released, it may take some time before you begin to see your favorite apps show up in the Mac App Store. Developers will need to work on updating existing apps, or developing new apps, during the beta program and that often carries over past the official release. 

Why should you care?

Take a look at the difference between the iOS App Store and Mac App Store in terms of quality and quantity and it quickly becomes apparent the Mac App Store is lacking all around. Developers just don't invest their time into developing apps for the Mac.

But if Apple can provide developers with a simple tool so that it takes only a few minutes to create a Mac version of their iPad app, we're likely to see the number of high-quality Mac apps increase. 

In theory, apps like Netflix, Instagram, Twitter or YouTube could wind up on the Mac. The long-term goal of Project Catalyst is to combine iOS and Mac apps so developers don't have to pick and choose which hardware to support. They build an app once, and it works across all your Apple devices. It's a scenario that benefits users and developers alike. 

Not to mention that learning how to use one version of the app, or finding and sticking with an app you love across all your devices, is super convenient. 

Published June 1, 2019. 
Update, June 3 at 12:44 p.m. PT: Added Apple's official name, more details.