Does Mac Catalyst support Background Processing?

My question is, does a Mac Catalyst app support background processing after the user quits the app?

No. More specifically, the BackgroundTask framework will not launch your app on macOS, though I believe your tasks may run if your app is running already. The issue here is that because the macOS app model and interface is so different than iOS, the system generally avoids launching apps "automatically" instead of trying to replicate the way iOS works.

Running the Settings app and going to General -> Login Items & Extension, I do not see my app under the App Background Activity section. Does it need to be listed there? If so, what steps are needed to get it there?

Sort of. That UI is tied to macOS APIs/features which can be used to provide somewhat similar functionality; however, this area of the system is so different than iOS that the APIs aren't really direct equivalents.

That leads to here:

If this is all documented somewhere, I'd appreciate a link since I was not able to find anything specific to making this work under Mac Catalyst.

What you're looking for is "SMAppService". That's the high-level API for managing LaunchAgents, which would let you create a helper process that runs in the background and does whatever you want/need.

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Kevin Elliott
DTS Engineer, CoreOS/Hardware

@DTS Engineer I really appreciate the response. Very helpful. After looking into SMAppService, it does seem like a launch agent is most appropriate.

The biggest issue I have now is trying to figure out how to make this work. My app and its needs are very far from simple. I have a very large data model that is stored locally in a SQLite database and the user can optionally choose to sync their data via iCloud (CloudKit).

Trying to figure out how refactor all of the existing code and logic that deals with CKSyncEngine syncing, reading and writing the SQLite database, and updating the in-memory data model into the launch agent, all in a way that can be coordinated with the main GUI app (when it might happen to be running), it going to be, shall I say, challenging.

Oh, and doing this in such a way that doesn't change how the iOS version currently works using background tasks.

Yep, that’s definitely a challenge.

In these situations I like to turn my agent into a ‘server’ and have the GUI app be a client of that server. And if you implement the client-server IPC using XPC, you have a number of ways to make that work on iOS:

• In iOS 26, you can actually put it into a separate process courtesy of the new helper extension feature.
• If you need to support older systems and want to preserve the XPC-ness of things, you can use an anonymous listener. TN3113 Testing and debugging XPC code with an anonymous listener talks about this, and while its focus is testing and debugging, there’s no reason you can’t use this in production.
• With NSXPCConnection, you can cut out the XPC layer entirely and use the real objects for your proxy objects.

In your case another option might be to run the agent and GUI app as completely separate things, and let your CloudKit syncing keep them in sync. That’s certainly keep your synching logic honest (-:

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Quinn “The Eskimo!” @ Developer Technical Support @ Apple
let myEmail = "eskimo" + "1" + "@" + "apple.com"

Thanks Quinn. Good information.