Sendable

In the previous post, we looked at running work in parallel with async let and TaskGroup. But once tasks start running in parallel, there’s a bigger question: what happens to the data they share? Swift’s answer is the Sendable protocol. What is Sendable? Sendable is a marker protocol that tells the compiler a type can safely be passed across concurrency domains like tasks and actors. If a type isn’t Sendable, Swift will stop you from moving it into a concurrent context because that might cause a data race. The compiler does a lot of this checking automatically, but sometimes you’ll need to be explicit. ...