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Quick Tip

Delay an async Task in Swift using the new clock APIs

In Swift 5.7 we have new APIs for interacting with time, that consist of three main components: clock, instant and duration. We can use these new APIs to delay an async Task in a more descriptive way than with the old API that accepted nanoseconds.

In the following example, we use Instant.now property to get the current instant, and add a Duration of 10 seconds to delay the task by 10 seconds. We can also specify a duration for tolerance, which would allow the underlying scheduling mechanisms to slightly adjust the deadline if necessary for more power efficient execution. We can choose either continuous or suspending clock, depending on whether we would like it to continue incrementing while the system is asleep.

Task {
    print("starting the task")
    try await Task.sleep(
        until: .now + .seconds(10),
        tolerance: .seconds(2),
        clock: .suspending
    print("continuing the task")