I've recently started to investigate web frameworks for swift, and specially the concurrency part. So just to clarify something : current swift web frameworks ( and ios apps for that matter) rely on grand central dispatch, which is a decent library for spawning work on work queues, managed by the OS, and dispatched on OS threads.
This type of model is fine and has worked quite well in the past. It is not event loop like node, nor light threads ( like go), nor actors like erlang, but it does work fine. And since swift is fast, it'll probably work just a fine as your python / ruby / node backend.
What we're looking for for the future of swift is something better / safer than that. But my personnal conclusion is that it shouldn't prevent you from building regular webservice api with this language.
This type of model is fine and has worked quite well in the past. It is not event loop like node, nor light threads ( like go), nor actors like erlang, but it does work fine. And since swift is fast, it'll probably work just a fine as your python / ruby / node backend.
What we're looking for for the future of swift is something better / safer than that. But my personnal conclusion is that it shouldn't prevent you from building regular webservice api with this language.