Swift, should you learn it or not?

It depends on what you think the long term future of Apple is. ObjC will still be widely used next for the next 5, even 10 years. It's been used by NextSTEP, then Apple for the past 25 years, so there's a ton of code out there and more still being written every day. But after Apple completes their transition to Swift (years away), will they continue to dominate as it has for the past 5 years? Maybe; maybe not. As an Apple developer I'm going to dabble in it, but I wouldn't stress about becoming an expert it right away.