循环中的快速延迟

Question

我有这个延迟功能:

func delay(delay:Double, closure:()->()) {
    dispatch_after(
        dispatch_time(
           DISPATCH_TIME_NOW,
           Int64(delay * Double(NSEC_PER_SEC))
    ),
    dispatch_get_main_queue(), closure)
}

从这里: dispatch_after - GCD在swift？

这段代码:

func start(){
   for index in 1...3 {
      delay(3.0){
         println(index)
      }
   }
}

3秒后,它给出:

3

3

3

我的目标:

3秒后:1

6秒后:2

9秒后:3

我该如何实现这一目标？谢谢,

Answer 1

尝试将延迟与索引相乘

func start(){
   for index in 1...3 {
      delay(3.0 * index){
         println(index)
      }
   }
}