What is the difference between OperationQueue and DispatchQueue in terms of their usage?

DispatchQueue is a low-level mechanism from Grand Central Dispatch (GCD) for asynchronous task execution. It is very lightweight and efficient but does not provide additional task management features.

OperationQueue is a higher-level API built on top of GCD. It allows creating Operation objects (tasks) that can be paused, canceled, have dependencies set between them, and their state can be tracked.

Example differences:

• DispatchQueue is suitable for simple asynchronous code execution.
• OperationQueue is convenient when managing complex chains of tasks, their priorities, and cancellations.

let operationQueue = OperationQueue()
let operation1 = BlockOperation {
    print("Task 1")
}
let operation2 = BlockOperation {
    print("Task 2")
}
operation2.addDependency(operation1) // operation2 will execute after operation1
operationQueue.addOperations([operation1, operation2], waitUntilFinished: false)

While DispatchQueue does not support dependencies directly.