How are parallel tasks implemented and managed in multithreaded programming?

In iOS, parallel tasks are usually implemented using:

• Grand Central Dispatch (GCD) — allows creating task queues (serial or concurrent) and executing them asynchronously or synchronously.
• Operation and OperationQueue — a higher-level API for managing task dependencies and priorities.

Example of using GCD for parallel execution:

DispatchQueue.global(qos: .background).async {
    // Long-running task in the background
    let result = performHeavyTask()
    DispatchQueue.main.async {
        // UI update on the main thread
        updateUI(with: result)
    }
}

Thus, parallel tasks are managed through queues, which allows efficient use of device resources and prevents blocking the main thread.