"concurrency needs of the average app" is different from what Go does well with green threads; this seems like something Swift does notably worse, but well enough that it doesn't annoy you in your use case. I feel like this is a different standard from "if Go can do it, Swift can do it better".

Isn’t that just a bridge to an existing OS level feature? Also is GCD green? (As in light weight, co-operative muti-threading)

>Isn’t that just a bridge to an existing OS level feature?

Yes. A feature well designed for this very purpose.

>Also is GCD green?

GCD tasks are not green threads but they're not direct threads either (even though they're used under the hood). They're more lightweight and much faster to create (than direct OS threads).