NSOperationQueue and concurrent operation

Question

As stated in the NSOperationQueueReference Reference: On iOS, operational queues are not used Grand Central Dispatchto perform operations. They create separate threads for non-competitive operations and start parallel operations from the current thread.

But I found in iOS 4.2.1, the queue always creates threads for concurrent or mismatched operations. And I think that the queue does not care about parallel or noncompetitive at all, because the breakpoint in isConcurrent is never interrupted. So I think the link was wrong ...

Answer 1

NSOperation, Mac 10.6 ( iOS 4.0), isConcurrent.

, NSOperation - .

Answer 2

NSOperationQueue GCD. :

iOS 4 Grand Central Dispatch .