https://stackoverflow.com/q/77597275/1271826

CancellationErrorDemoViewController.swift

class ViewController: UIViewController {
    private var task: Task<Void, Never>?

    override func viewDidLoad() {
        super.viewDidLoad()

        let task = Task {
            do {
                try await self.test()
            } catch is CancellationError {              // this is another way to check for `CancellationError`
                print("Task canceled..")
            } catch {
                if Task.isCancelled {
                    print("cancelled in catch block..") // we should never get here as the func should have thrown `CancelationError`, caught above
                }

                // whatever non-cancellation error handling you want here
                print(error)
            }
        }
        self.task = task

        Task {
            try await Task.sleep(for: .seconds(1))
            task.cancel()
        }
    }

    nonisolated func test() async throws { … }
}