A couple of years ago I wrote about learning every year.
This year, although being very busy professionally, I've still be able to do a couple of personal projects which were focused around learning the programming language Swift. I've developed a couple of small useful apps that provide functionality across macOS, iOS, and watchOS.
I'm long way away from even calling myself competent, but it's been a good exercise in using new tooling (xCode), building common code for multiple form factors, and better understanding the trade-offs between building web apps versus native for these devices.
I've not published either to the App Store (yet) but have been using them myself weekly.