Process Array in parallel using GCD

Question

I have a large array that I would like to process by handing slices of it to a few asynchronous tasks. As a proof of concept, I have the written the following code:

Answer 1

You can also use concurrentPerform(iterations: Int, execute work: (Int) -> Swift.Void) (since Swift 3).

It has a much simpler syntax and will wait for all threads to finalise before returning.:

DispatchQueue.concurrentPerform(iterations: iterations) { i in
    performOperation(i)
}