I’ve been programming for decades, though usually for myself, not as a profession. My current go-to language is Python, but I’m thinking of learning either Swift (I’m currently on the Apple ecosystem), or Rust. Which one do you think will be the best in terms of machine learning support in a couple of years and how easy is it to build MacOS/ iOS apps on Rust?
Other than having first class support on Apple's hardware Swift dosen't have much going for it. There is no killer feature in Swift, it dosen't widespread features and it only has a small niche. If you want to develop for mainly Apple devices I would say go for it as that is the niche it was designed for. Although I see from your post you want to do ML, Python for the high level stuff + C++ for the low level stuff is probably your best pick for that. May I ask what type of ML are you going for? Are you mainly using libraries like Tensorflow, Pytorch etc... or are you into the nitty gritty of building these things yourself and writing the required code for the matrix math and training algorithms.
But I'm obviously on team Rust^^ for various reasons (one being that you can do the whole stack in Rust (not that it's necessarily the best choice for each level, but it really composes well and with a little bit of trait-magic abstraction in the higher levels it works quite well IME)
For ML, python yes, certainly for high-level stuff at least currently. I wouldn't be so sure in the future about the lower stack though, Rust seems to gain momentum there as well (potentially replacing use-cases where currently python is dominant too).
I think ML is probably going to require a lot of people in the future and I'm looking to build a digital nomad skill set for the future that pays well. While I've done a postgrad subject on ML and have a STEM degree, but I'm inclined to use existing libraries as that's just easier.