ios - 如何取消GCD队列？

Question

我需要知道串行 GCD 队列上尚未启动的任务数。原因是我希望他们“取消”，像这样:

if(!canceled) {
    ... do work
  }

Answer 1

多亏了 Midhun MP 的更换真的很容易:

    dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), {
// .. some code
    //HERE I need cancel queue, but with GCD it is not possible
    })

所以使用NSOperationQueue的解决方案:

    var oq = NSOperationQueue()
    oq.addOperationWithBlock({
// .. some code
    oq.cancelAllOperations()
    })