What task is solved using the main queue in the system?

In iOS, the main queue is responsible for executing all operations related to updating the user interface and handling user events. It runs on the main thread of the application.

The main queue's task is to ensure the sequential and safe execution of code that interacts with the UI, as UIKit is not thread-safe. All interface changes should occur specifically on this queue.

Example of usage:

DispatchQueue.main.async {
    // UI update
    self.label.text = "Updated"
}

Thus, the main queue guarantees that the UI will be updated correctly and without failures.