That documentation is great! Thanks Albert! Trying to find documentation can be tricky sometimes. You mentioned in your original reply that you "suggest you do two separate Build and Archive processes, one for iOS and one for Mac Catalyst." Why do you recommend that instead of trying to build a bundle that includes both? I'm not against the idea of just archiving my Catalyst build separately and submitting to the App Store separately, I'm just curious.

I am running Xcode 26.5. I have not moved to trying one of the 27 betas yet. So I assumed (and maybe incorrectly) that you would be able to archive once for an app that can generate both a Catalyst build AND an iOS build. Since it’s the same source code and bundle either way it just seemed like it should be a single process. I couldn’t find documentation on how a universal Catalyst/iOS bundle was structured, but maybe that’s because they don’t exist as one archive process. What do you mean by “You can also create a multiple platform and then add Mac Catalyst: “For Mac Catalyst builds, this target and its dependencies will link or embed only Mac-compatible content, and the security and App Sandbox settings will be aligned with the iOS app.” That sounds similar to a universal binary which is maybe where my confusion lies. Thank you for helping out. I greatly appreciate it. :)