When to use Semaphore instead of Dispatch Group?

Question

I would assume that I am aware of how to work with DispatchGroup, for understanding the issue, I\'ve tried:

class ViewController: UIViewController {
    override         


        

Answer 1

Semaphores and groups have, in a sense, opposite semantics. Both maintain a count. With a semaphore, a wait is allowed to proceed when the count is non-zero. With a group, a wait is allowed to proceed when the count is zero.

A semaphore is useful when you want to set a maximum on the number of threads operating on some shared resource at a time. One common use is when the maximum is 1 because the shared resource requires exclusive access.

A group is useful when you need to know when a bunch of tasks have all been completed.