How do you get off the main thread in Swift 6.2?

Jacob Bartlett (@jacobtechtavern) on Swift 6.2 concurrency.

Key Point

Use Task { @concurrent … } — the slightly less sexy younger brother of the raw @concurrent function attribute.

Behavior

It creates a new unstructured task that explicitly opts out of main actor isolation, scheduling the work on Swift's global concurrent executor.

Code Example

func calculateScoreTaskConcurrent(label: String, iterations: Int) async -> Int {
    let task = Task { @concurrent in
        var total = 0
        for value in 0..<iterations {
            total = (total &+ value) % 97_531
        }
        return total
    }
    return await task.value
}

The caller continues (or returns) immediately, with the new task body running separately. This is why we need to suspend at the return, awaiting the result.

Thread Behavior

We sit on thread one prior to the task body and hop off the main actor once inside the Task body.

Link

• 3 Levels of Swift 6.2 Approachable Concurrency