I've been compelled to make an application because I'm weary of the standard interfacing of iOS. Yes, I understand how much market there is for iPhone and iPad applications, but I prefer my desktop for doing work, I prefer my keyboard to the virtual stuff presented. There's still plenty of folks like me, and frankly, there'll continue to be as the generations staring at their little screens start needing glasses....

I'm aware of the ' Catalyst' option in Xcode, and I'm convinced it's best to learn SwiftUI and contentView rather than the storyboard paradigm, but still there's a dearth of practical advice and tutorials focused on desktop applications. I'm trying to duplicate a complex interface structure involving a split view with each view split yet again. One divider controls the horizontal sections and each of those are split vertically. Each partition must be resizable and independent of the others. In storyboard this can be done - albiet a bit of a pain, but in SwiftUI I'm stuggling as there's no immediate feedback as there is in storyboard.

Soooo - my question at this point is while I've built a general application window that's divided horizontally with user resizable sections, I'm stumped as to how I can further divide the sections into upper an lower halves (also resizable). I'm thinking the geometry reader is being instantiated too many times perhaps. This is my first posting so I'm not sure if I should provide the file contents or wait for whomever might have an interest.

If you want to build apps for macOS then would recommend Start with Paul's book Hacking with macOS so you can get the basic of macOS, and think they mention NavigationSplitView and more