Will Swift Concurrency deploy back to older OSs?

It is tempting to try to just put it into one bucket or another, but respectfully I feel that this is an oversimplification.

Concurrency, as a whole, is a language feature. It requires specific runtime support. Most languages, including Objective-C and C++, have language runtimes that provide logic that power many language features. On Apple platforms, that runtime support ships with the OS.

In the case of backward deployment on Apple platforms, it is about finding a way to provide the needed runtime components for concurrency when the underlying OS does not provide it. I'm not saying that is or isn't possible; Swift definitely has provided backward deployed runtime support for a variety of features before.

All I am saying is that is that backward deployment of concurrency earlier than iOS 15, as of right now, does not exist, and that the Xcode 13 release notes may accidentally be interpreted that this is a "known issue" rather than something that just isn't there. As folks need to make choices regarding their applications' minimum deployment targets, I just wanted to clarify that concurrency, as of right now, requires iOS 15 and higher.