Completion block using GCD

问题:

I am developing an app that requires a completion block and a "barrier" functionality. As far as I know, NSOperation API has a completionBlock property and GCD API has the dispatch_barrier_(a)sync function to handle the barrier needs.

What should I do in order to accomplish both of the needs? Thanks!

回答1:

dispatch_group should have all the pieces you need. Just dispatch_group_async/dispatch_group_enter for your work units, then dispatch_group_notify for your completion handler.