我是否必须在操作队列本身上读取 NSOperationQueue 的 operationCount？
Do I have to read NSOperationQueue's operationCount on the operation queue itself?
有时 operationCount 似乎没有 return 正确的值。我必须从队列本身访问它还是从其他线程访问它并不重要？
"the value returned by this property reflects the instantaneous number of operations at the time the property was accessed."
它不能保证精确/稳定，你不应该用它来做计算/决定
有时 operationCount 似乎没有 return 正确的值。我必须从队列本身访问它还是从其他线程访问它并不重要？
"the value returned by this property reflects the instantaneous number of operations at the time the property was accessed."
它不能保证精确/稳定，你不应该用它来做计算/决定