Dispatch group on Swift example: how to wait for multiple asynchronous closures to complete

DispatchGroupSwift5Example.swift

let group = DispatchGroup()

group.notify(queue: .main, work: DispatchWorkItem(block: {
    print("everything finished")
}))

func asyncOne() {
    sleep(2)
    group.enter()
    print("finished A")
    group.leave()
}

func asyncTwo() {
    sleep(2)
    group.enter()
    print("finished B")
    group.leave()
}

asyncOne()
asyncTwo()