I'm surprised no one has mentioned this but I'd say the #1 resource for learning the practical 'how do I get X thing done in a couple of hours' are tutorials on https://www.raywenderlich.com/ without a doubt.

It has tutorials for every basic question imaginable in a very easy to follow manner.

It'll definitely take some time, as for being enjoyable - I don't get a kick out of learning an entire new set of libraries and idioms for achieving the same thing I can do in another toolset, but if you do, then great :)

One last thing - the amount of information for macOS is about 1% compared to iOS, so I'd definitely go the iOS route.