ViewController.swift

import UIKit

class ViewController: UIViewController {
    override func viewDidLoad() {
        super.viewDidLoad()
        
        Task.init {
            try await sleep()  // 何秒かかる？
        }
    }
    
    func sleep() async throws {
        async let a = Task.sleep(nanoseconds: 2_000_000_000)
        async let b = Task.sleep(nanoseconds: 5_000_000_000)
        print(try await a, try await b)
    }
}