swift3.0 GCD

    var myQueue: DispatchQueue?
    var myQueueTimer: DispatchQueue?
    var myTimer: DispatchSourceTimer?
    var myGroup: DispatchGroup?
    var mySource: DispatchSource?

//MARK: - 并行队列   没有attributes，默认是串行队列
        myQueue = DispatchQueue(label: "myQueue",attributes:DispatchQueue.Attributes.concurrent)
        myQueue?.async {
            for _ in 0...10 {
                NSLog("......")
            }
        }
        myQueue?.async {
            for _ in 0...10 {
                NSLog("++++++");
            }
        }
        //MARK: barrier 会等待上面执行完毕再执行下面的，会阻塞当前线程
        myQueue?.async(flags:.barrier ,execute: {
            NSLog("000000")
        })

        myQueue?.async {
            NSLog("111111")
        }
 //MARK: - 信号量
         //初始化信号量，计数为2
        mySemaphore = DispatchSemaphore.init(value: 2)
        for i in 0...10 {
            NSLog("----i:%d----", i)
            mySemaphore?.wait()  //获取信号量，信号量减1，为0时候就等待,会阻碍当前线程
            myQueue?.async {
                for j in 0...4 {
                    NSLog("%d++++j:%d",i, j)
                }
                self.mySemaphore?.signal()  //释放信号量，信号量加1
            }
        }
//MARK: - 延时提交任务
        myQueue?.asyncAfter(deadline: DispatchTime.now() + 10, execute: {
            NSLog("6666")
            self.stopTimer()
        })

//MARK: - 串行队列        默认串行队列
        myQueueTimer = DispatchQueue(label: "myQueueTimer")
        myQueueTimer?.async {
            for _ in 0...10 {
                NSLog("aaaaaaa");
            }

        }
        myQueueTimer?.async {
            for _ in 0...10 {
                NSLog("bbbbbbb");
            }
        }

//MARK: - 重复提交任务
        //      秒               毫秒                      微秒                      纳秒
        //  1 seconds = 1000 milliseconds = 1000,000 microseconds = 1000,000,000 nanoseconds
        myTimer = DispatchSource.makeTimerSource(flags: [], queue: myQueueTimer!)
        myTimer?.scheduleRepeating(deadline: .now(), interval: .seconds(1) ,leeway:.milliseconds(100))
        myTimer?.setEventHandler {
            NSLog("fff")
        }
        myTimer?.resume()


//MARK: - Group
//MARK: notify
        myGroup = DispatchGroup()
        myQueue?.async(group: myGroup, qos: .userInitiated, execute: {
            for _ in 0...10 {
                NSLog("1a1a1a1a1a1a")
            }
        })
        myQueue?.async(group: myGroup, qos: .userInitiated, execute: {
            for _ in 0...10 {
                NSLog("2b2b2b2b2b2b")
            }
        })
        //执行完上面两个任务才执行下面的这个任务，不会阻塞当前线程
        myGroup?.notify(queue: myQueue!, execute: {
            NSLog("3c3c3c3c3c3c")
        })
        NSLog("next")

//MARK: wait
        myQueue?.async(group: myGroup, qos: .userInitiated, execute: {
            for _ in 0...10 {
                NSLog("==========")
            }
        })
        myQueue?.async(group: myGroup, qos: .userInitiated, execute: {
            for _ in 0...10 {
                NSLog("------------")
            }
        })
        //等待上面任务执行，会阻塞当前线程，超时就执行下面的，上面的继续执行。可以无限等待 .distantFuture
        let result = myGroup?.wait(wallTimeout: .now()+2)
        if result == DispatchTimeoutResult.success {
            NSLog("ok.")
        } else {
            NSLog("time out.")
        }
        NSLog("next")

//MARK: enter leave 手动管理group计数,enter和leave必须配对
        myGroup?.enter()
        myQueue?.async(){
            for _ in 0...10 {
                NSLog("+++++++++++++")
            }
            self.myGroup?.leave()
        }

        myGroup?.enter()
        myQueue?.async(){
            for _ in 0...10 {
                NSLog("------------")
            }
            self.myGroup?.leave()
        }

        myGroup?.notify(queue: myQueue!, execute: {
            NSLog("=")

        })

类似OC 中的GCD,只是调用方法不同，更方便，如下代码，功能为刷新tableview；

 

DispatchQueue.main.async(execute: {

    self.listTableview.reloadData()

})