Where is monitoring and tracking of completed tasks carried out?

In iOS, monitoring and tracking completed tasks are usually done using classes from Grand Central Dispatch (GCD) and OperationQueue.

• DispatchGroup allows grouping multiple asynchronous tasks and tracking their completion.
• OperationQueue and Operation provide a higher level of abstraction, where you can monitor the state of operations through properties like isFinished, isExecuting, and use delegates or KVO.

For example, with DispatchGroup, you can execute code after all tasks are completed:

group.enter()
DispatchQueue.global().async {
    // task
    group.leave()
}
group.notify(queue: .main) {
    // code after all tasks are finished
}