2
的关系,我很困惑与DispatchQueue和DispatchSemaphore.Like下面的例子:[游乐场] bettwen DispatchQueue和DispatchSemaphore
let semaphore : DispatchSemaphore = DispatchSemaphore(value:1)
for i in 1...40 {
DispatchQueue.global().async{
semaphore.wait()
NSLog("......1-%d",i)
semaphore.signal()
}
}
我认为它应该打印1 ... 40,其实,它只能打印约25中,结果如下所示:
2016-11-18 19:05:38.786 MyPlayground[7436:495171] ......1-1
2016-11-18 19:05:38.787 MyPlayground[7436:495175] ......1-2
......
2016-11-18 19:05:38.797 MyPlayground[7436:495258] ......1-23
2016-11-18 19:05:38.797 MyPlayground[7436:495244] ......1-24
有谁知道原因吗?
感谢