@granada29: Thanks. That could well be the right way to go. Over the next few days I will be looking at Swift and try to learn how this all fits together. Big job!

Hi – thanks for the quick replies. @darkpaw: Thanks – yes, I will look at the samples on Apple's website. I accept that I will have to learn either Swift or Objective C – but hopefully I can wrap them up and call them easily from C++. @ssmith_c: Thanks. Ok, I didn’t know about Objective C++. That might well be the direction for me. So, AppKit is the Objective C API for GUI programming? My issue is that I have a large app written for Windows in C++ which I want to port – hence my need for C++. It handles its own localization. I will definitely have to learn about packaging, signing and notarizing the Mac way. I’ve just had a quick play with XCode writing a console app in C++. All seems fairly straight forward. Debug/Release, debugging, setting the C++ version etc. was all pretty quick with a few google searches. I am happy (and expect) to learn new things. I have used a Mac for a long time (15+ years), so I understand (mostly) the ecosystem. I am just hoping to find a way to rewrite as little as possible for the port. @endecotp: 85% C++, 15% objC++?? That is very encouraging! Yes, I was expecting a GUI rewrite. I will definitely look at the Swift UI examples. As you say, this is my best place to start. Creating my own GUI framework was the first thing I did in the Windows version (by that, I mean my own C++ classes which wrapped up the Win32 and other APIs). Maybe I can do a similar thing on macOS by (eventually) writing C++ classes that wrap up calls to Swift. I don’t know yet – I need to look at Swift and the AppKit first. Thanks to everyone for all your help. Best regards AW