Developers using Apple’s system to convert iPad software to macOS say Catalyst still needs lots of work before it can fulfill its promise.

The functionality is mostly there, but some features are missing and there are complaints about the style of the resulting apps.

Catalyst catalyzes macOS development

There are far more iPhone and iPads apps than there are macOS ones. A highlight of the just-released macOS Catalina is Catalyst, which intended to allow third-party developers to easily port their iPadOS software to Mac.

Apple says that “Starting with Xcode 11, you can create a Mac version of your iPad app using Mac Catalyst. Configuring your app to run in macOS takes just a click in a checkbox.”

Developer James Thomson tested porting his PCalc app from iPad to Mac, and found that Catalyst really does work.

However, he ran into limitations. “Multiple window support works, but I ran into a lot of problems,” he noted in a blog post. “Some APIs like the share sheet are just not present.”

And perhaps because iPads don’t come with keyboards, Catalyst doesn’t fully support them either. “There’s still no direct way to read the state of the keyboard,” said Thomson. He points out that’s going to cause problems for games that use keyboard controls.

And he’s not alone. Developer Steve Troughton-Smith frequently uses his Twitter account to discuss the limitations of Catalyst, though he also has posted many positive comments as well.

I really, really hope Apple is aggressive with updating Catalyst (and UIKit on iOS) to add missing functionality that various kinds of desktop apps need (like key up events). It would suck to have to wait a whole year just to see any progress

— Steve Troughton-Smith (@stroughtonsmith) October 8, 2019

Still, both he and Thomson have criticized a lack of documentation for macOS Catalyst.

A question of style

As noted, Catalyst was able to make the iPad version of PCalc into a Mac app with almost no work. But that doesn’t mean Thompson is happy with the result. “The ‘single check box’ Catalyst version of PCalc is a single resizable window, with many tables and popovers that seem to me to be out-of-place on the Mac.”

Apple’s developer site offers a guide called “Optimizing Your iPad App for Mac”. This shows developers how to control what appears in  the Menu Bar and the Preferences Window of a macOS app, as well as giving other assistance. It’s clear that creating a high-quality macOS app out of an iPad one takes more than clicking a check box.

Thompson said, “I am hopeful that this is just a 1.0 (if you count the Mojave apps as a public beta), and things will continue to improve.”