The two languages are pretty different and I don't see much logic in learning the "harder" one then the easier one.
I put harder in quotes because ObjC is harder for some. IDK of you can do finer things with ObjC vs Swift, both seem to have the same power.
If you're looking for a job, I'd look at what the job market is asking for. Right now only about 10% of the top 100 apps are using Swift. Swift doesn't have the legacy code the ObjC has and it'll be a long time before people go back and rewrite most of the legacy code in Swift.
Most advanced apps have legacy ObjC code and there's not much reason to convert it.
I'm learning Swift just because of the job market, but I don't see that knowing ObjC helps because Swift isn't like any other language I've learned.
IMO, you really need to think about your goals. If you're making games, maybe Unity would be the better choice and Unity uses C#.
Are you going to make games?