Authenticator with Swift Concurrency

[bluelagon]

Authenticator with Swift Concurrency

[jshier]

There's no need to use a semaphore (and using a DispatchSemaphore is dangerous in Swift concurrency). Instead, you can use a Task directly and call the completion handler.

func refresh(_ credential: Credential, for session: Session, completion: @escaping (Result<Credential, Error>) -> Void) {
  Task {
    let result await someAsyncAPI()
    completion(result)
  }
}

I have no plans to offer a duplicate API surface for Alamofire's protocols barring a deep need, given you can simply call the completions inside Tasks. If such a need does arise it could be considered, but I haven't seen any examples that don't work manually right now.

[bluelagon]

Thank you for your time and for your answser.

In fact, I was using a semaphore in order to allow only one call to the refresh tokens API, so that other calls asking for a refresh would be in a waiting state. If I'm not wrong, in the example you provided, multiple tasks are possibly launched if they occurs during the refresh of the first call.
And if I want to acheive this, the someAsyncAPI method should have a mechanism of allowing only one call at a time.

[jshier]

Using Alamofire's AuthenticationInterceptor should do that for you, otherwise there are many ways to structure such a wait so that it doesn't use unsafe constructs like a DispatchSemaphore.