While I already knew some Swift, now I use mostly Linux and I'm starting to use Swift in Linux. Although it has been eight months in Linux, it's still missing some parts (particularly libdispatch for async) and a good IDE, but most of those problems seem that will be fixed soon. I chose Swift because it will let me interface easily with any C library, I've already worked with pulseaudio and avahi, after that I want to learn SDL and a lot of other C libraries that I haven't tried because of C