In short:
Objective-C, Cocoa, and the applications that Mac OS X provides to developers (not just Xcode and Interface Builder).
Slightly longer:
I love the Objective-C syntax and the countless features Cocoa provides. You can do so much when writing applications for Mac OS X without even having to write one line of code. And you can do even more things when you write just a very simple “glue code”. And when you need to write "real" code to implement something that is not yet in one of the frameworks, it is not so tiring, because, in my opinion, writing Objective-C code is fun.
The market is also interesting, for example, there are many areas where Mac software is simply missing, so you can be the first to make a request for a specific task, which can be great news for a new company. Intrude. The market is also disappointing, although I think people expect too much from Mac software these days, at least I do. Mac software should not only be absolutely reasonably good in terms of technical implementation and usability / intuitiveness, it should also look beautiful or cool or whatever. This makes it really difficult for some software stores, for example. You must be a coder and designer, and this indicates the impossibility, although, of course, there are exceptions. Compare this to Linux, for example, where everyone is happy with the standard GUI tools that the graphical interface system provides. Maybe it is not as bad as I think it is, however, it is just my impression, and I may be dead wrong.
I have not programmed much on Mac for about three years, but every time I develop an application in Java, C #, Ruby, C, or something else that I use, I get my brain about writing an application in Objective -C instead of Xcode. But then I also think about how to use cross-platform software instead of software that only works on Mac OS X. I use Windows, Mac OS X, Linux, and some lesser-known operating systems, and I can use applications. which I write on each of these platforms, and not just on a Mac, is too nice to refuse. That's why I mainly develop cross-platform software these days, although I like developing Mac OS X better.