ios - 方法不等到再次运行

Question

我有一个从框架中多次调用的委托(delegate)方法，我需要它在再次运行之前等待显示所有字母。我试过 dispatch_async(dispatch_get_main_queue()，但是当再次调用时，该方法的另一个实例运行。

  var myInt = 1

            for letter in message.characters {

                let delay = 0.1 * Double(NSEC_PER_SEC) * Double(myInt)
                let dispatchTime = dispatch_time(DISPATCH_TIME_NOW, Int64(delay))

                dispatch_after(dispatchTime, dispatch_get_main_queue(), {
                    self.textView.text = self.textView.text + String(letter)
                })

                myInt = myInt + 1
            }
            self.textView.text = self.textView.text + "\n"

Answer 1

创建一个串行队列

let delegateQueue = dispatch_queue_create("com.domain.delegateQueue", DISPATCH_QUEUE_SERIAL)

在委托(delegate)方法中

dispatch_async(delegateQueue, ^{
    //all the things done in delegate method
})