Swift - Not wait for async to return

Question

I'd like to be able to let the function doSomething() from class B to not be async and to not block it's caller thread. But with the following code I get this error:

Cannot pass function of type '() async -> Void' to parameter expecting synchronous function type

and xcode try to enforce the doSomething() function from class B to be an async

class A {
    func doSomething() async throws {
       //perform 
    }
}

class B {
   let a = A()
   func doSomething() {
      DispatchQueue.global().async {
        do {
           await try a.doSomething()
        } catch {
           print(error)
        }
     }
  }
}

score 20 · Accepted Answer · edited Jul 04 '22 at 17:54

20

You can wrap the function in a Task, Task

func doSomething() {
      Task {
        do {
           try await a.doSomething()
        } catch {
           print(error)
        }
     }
  }

edited Jul 04 '22 at 17:54

ZiggidyCreative

335
3
16

answered Oct 12 '21 at 12:07

cora

1,916
1
10
18

hmmm, I have this code in Swift Package and got this error `Cannot find 'Task' in scope` – barola_mes Oct 13 '21 at 06:00
ok I see, it is iOS 15+ – barola_mes Oct 13 '21 at 06:13
2

With Xcode 13.2 it's possible to use all of the new Concurrency APIs in iOS13+. https://developer.apple.com/documentation/xcode-release-notes/xcode-13_2-release-notes – halil_g Jan 25 '22 at 05:27
1

But this way, await will happen on Main queue thus blocking main thread which is opposite from `DispatchQueue.global().async` goal – mixtly87 Apr 04 '22 at 16:25
1

@mixtly87 That depends. See https://stackoverflow.com/a/67954900/978300 – Giles Apr 28 '22 at 09:31

Swift - Not wait for async to return

1 Answers1