Can you explain the difference between a global queue and a background task queue?

In iOS, the global dispatch queue refers to the system queue provided by GCD (Grand Central Dispatch), designed for executing tasks in the background with varying priority levels. It is shared across the entire application and optimized by the system for efficient resource distribution.

A background task queue (e.g., Background Task Queue) is a queue that you create yourself or use for executing tasks that should run in the background, possibly with time or resource constraints (e.g., data loading, synchronization).

Main differences:

• Global queue — a system-wide, shared queue with predefined priorities, does not require creation.
• Background queue — can be created by the developer for specific tasks, allowing control over the order and execution features.

Example of using a global queue:

DispatchQueue.global(qos: .background).async {
    // Background task
}

If a queue with more precise control is needed, create a custom one:

let backgroundQueue = DispatchQueue(label: "com.example.backgroundQueue", qos: .background)
backgroundQueue.async {
    // Background task
}