> other languages don't have a similar barrier

Lisps have the RPN psychological barrier. Python has the significant whitespace psychological barrier. etc. Any language can present someone with some psychological barrier.

I think the OP's strongest point was, Objective-C the language is pretty trivial to learn quickly (after all, it's just C with message passing). You'll spend far longer trying to learn the Cocoa APIs than you will spend learning Objective-C-the-language.

For instance, I decided to try to learn swift and SpriteKit at the same time. I spent far longer looking up methods on SKSpriteNode than I did looking up language constructs. (i.e. I assumed "let" was the same as in ES6 and couldn't figure out why the compiler was mad.)

Okay, I meant more that there's not a skills barrier in terms of actually learning to use the language. The syntax can be intimidating, but once you've spent a couple of hours with it, it's not an issue any more.

It's far more difficult to get to grips with how the APIs work.