[danudey]

Xcode doesn't use an emulator. When you build for the simulator it's building an x86_64 binary that runs natively.

Also, to your other point (UI integration), my assumption is that you'll need to make a different UI for macOS than you do for iPhones (you have to do the same for iPads, IIRC, even if you're just creating a larger version of the existing iPhone UI).

So if you have a simple way of handling it, you end up with all of your core logic being shared between all versions, and multiple versions of the UI that you just hook up to your existing controllers.

[TheOtherHobbes]

But there's minimal non-trivial shared core logic, because the apps live in a different user space and do different things with different end goals.

You can port a Mac DAW to iOS - e.g. Cubase to Cubasis - but it's no longer the same product. Most of the features that make the desktop version so useful in a professional context are lost in translation, because iOS doesn't have the resources to support them.

So what do you gain by trying to merge development, except extra work and possibly extra confusion.