GNUstep was far from painless. I had the pleasure of trying to use it to port some Objective C code maybe 8 years ago and it was an absolute pain to deal with,

GNUstep was far from painless. I had the pleasure of trying to use it to port some Objective C code maybe 8 years ago and it was an absolute pain to deal with, not to mention that there were some implementation details which varied from the Apple implementation so your code would not behave consistently between platforms. Not to mention that it’s very different to have cross platform support as part of the core development process. With a 3rd party implementation like GNUStep,(especially one with a relatively small user base) there is no guarantee that it would keep pace with Apple’s implementation. Swift is a much smoother, modern experience. I am not saying it is perfect, and other languages have much better support across platforms, but to compare Swift and Objective-C is just not accurate.