NSOperationQueue对GCD

在什么情况下，您更喜欢使用 NSOperationQueue over GCD？

In what cases would you prefer to use NSOperationQueue over GCD?

我从这两个有限的经验，我认为与 NSOperationQueue 你基本上可以控制多少并发操作。

From my limited experience of these two, I take it that with NSOperationQueue you basically have control over how many concurrent operations there are.

对于GCD，你不能这样做，因为你正在使用队列。

With GCD you can't do this, since you are using a queue. Except you can somehow simulate this with a multi core processor, although still I think there's no way to control it.