Create a Mac version of an iPad app
With Xcode 11 and macOS 10.15, or later, you can use Mac Catalyst to build a Mac version of an iPad app. This version uses UIKit, but runs on macOS.
If you’re using Xcode 11.3 or earlier, you'll need to enable the Mac Catalyst capability and choose to have an App ID autogenerated for you.
As of Xcode 11.4, new apps built with Mac Catalyst can use the same bundle ID as the iPad app to support universal purchase. If you don’t want to distribute the apps together, you can register a different bundle ID. It’s highly recommended that you continue developing any in-progress apps built with Mac Catalyst using Xcode 11.4 or later.
Existing apps and Xcode 11.3 or earlier
If you’re using Xcode 11.3 or earlier, or you’ve already distributed your Mac app built with Mac Catalyst using an autogenerated bundle ID, follow the process below to register new app IDs to support new app extensions.
In Certificates, Identifiers & Profiles, click Identifiers in the sidebar, select your App ID from the list, scroll down and enable the Mac Catalyst capability, then click Configure.
Click Configure and select “Automatically create an identifier.” This was the default behavior in Xcode 11.3 and earlier.
Click Save on the top right to record the changes to your App ID.
If a dialog appears, click Confirm to finalize your changes.
With the release of Xcode 11.4, you can build apps for iOS, macOS, and tvOS using the same bundle ID. To build your app, create a Mac Catalyst Provisioning Profile and select your App ID. If you’d like to update an existing Mac app using Mac Catalyst and your app hasn’t been distributed yet, you don’t need to enable the Mac Catalyst capability.