Have you ever used the QoS mechanism in your projects?

Yes, in iOS, the QoS (Quality of Service) mechanism is used to manage task priorities, which helps optimize application performance and responsiveness. For example, when loading data from the network, QoS with the .userInitiated level can be used for tasks that the user expects to complete quickly, while background synchronization can use .background.

Example of using QoS with GCD:

DispatchQueue.global(qos: .userInitiated).async {
    // Execute high-priority task
}

This allows the system to efficiently allocate resources, improving user experience.