How can you determine when all asynchronous tasks in a queue using concurrency mechanisms are completed?

In iOS, to determine when all asynchronous tasks in a queue using concurrent mechanisms (such as DispatchQueue) are completed, DispatchGroup is often used.

DispatchGroup allows grouping multiple asynchronous tasks and receiving a notification when all of them are finished. Example of usage:

let group = DispatchGroup()

for task in tasks {
    group.enter() // notify the group about the start of a task
    DispatchQueue.global().async {
        // perform asynchronous task
        task()
        group.leave() // notify the group about the completion of a task
    }
}

group.notify(queue: DispatchQueue.main) {
    print("All tasks are completed")
}

Thus, group.notify is called when all tasks associated with the group are finished. This is a reliable way to track the completion of all asynchronous operations in a concurrent environment.