快速延迟问题

Question

所以我一直在创建一个应用程序，如果你按下按钮，它会触发startGame。然后，应该等待更改每个图像之前创建的延迟。延迟工作，但他们一开始我的应用程序启动，而不是当我按下按钮。自从我一直试图修复它。有什么建议么？

感谢您的帮助！

以下是我认为比较重要的代码：

let deadlineTime = DispatchTime.now() + .seconds(1) 
let deadlineTime2 = DispatchTime.now() + .seconds(2) 
let deadlineTime3 = DispatchTime.now() + .seconds(3) 
let deadlineTime4 = DispatchTime.now() + .seconds(4) 

@IBAction func startGame(_ sender: AnyObject) { 

     trumpImage.isHidden = false 

     DispatchQueue.main.asyncAfter(deadline: deadlineTime) { 

      self.trumpImage.image = UIImage(named: "trumpTurnOne") 

     } 

     DispatchQueue.main.asyncAfter(deadline: deadlineTime2) { 

      self.trumpImage.image = UIImage(named: "trumpTurnTwo") 

     } 

     DispatchQueue.main.asyncAfter(deadline: deadlineTime3) { 

      self.trumpImage.image = UIImage(named: "trumpTurnThree") 

     } 

     DispatchQueue.main.asyncAfter(deadline: deadlineTime4) { 

       self.runGame() 

     } 

} 

Answer 1

试试这个：

let deadlineTime = {return DispatchTime.now() + .seconds(1)} 
let deadlineTime2 = {return DispatchTime.now() + .seconds(2)} 
let deadlineTime3 = {return DispatchTime.now() + .seconds(3)} 
let deadlineTime4 = {return DispatchTime.now() + .seconds(4)} 

如果您已声明四个DispatchTime S作为实例属性，初始值的评价在生成实例时生成，而不是实际使用这些属性的时间。这意味着DispatchTime.now()表示实例化的时间，它可能比用户按下按钮更早。

因此，要使DispatchTime.now()代表按下按钮的时间，您可能需要使它们成为计算属性。否则，你需要把它们变成局部变量。

@IBAction func startGame(_ sender: AnyObject) { 
    let deadlineTime = DispatchTime.now() + .seconds(1) 
    let deadlineTime2 = DispatchTime.now() + .seconds(2) 
    let deadlineTime3 = DispatchTime.now() + .seconds(3) 
    let deadlineTime4 = DispatchTime.now() + .seconds(4) 

    //... 
}