中断animateWithDuration

Question

我有一个动画计时器条向下计数，我希望能够取消动画并在满足特定条件时重置条，因此它不会一直变为0.同样，如果它确实为0，我想调用一个函数。

现在我只需要一个按钮来测试。再次按下按钮可以防止它一直向下，但是它会在屏幕上弹出，并且完成块中的打印语句总是返回。我认为多个动画正在堆叠在一起。

如何停止动画？

var countDownBar = UIView() 
var button  = UIButton() 


override func viewDidLoad() { 
    super.viewDidLoad() 

    // Place the countDownBar in the center of the view 
    countDownBar.frame = CGRectMake(0, 0, 150, 15) 
    countDownBar.center = view.center 
    countDownBar.backgroundColor = UIColor.blueColor() 
    view.addSubview(countDownBar) 

    // Add in a button 
    button = UIButton.buttonWithType(UIButtonType.System) as UIButton 
    button.frame = CGRectMake(0, 0, 50, 20) 
    button.center = CGPointMake(view.center.x, view.center.y + 30) 
    button.backgroundColor = UIColor.lightGrayColor() 
    button.setTitle("button", forState: UIControlState.Normal) 
    button.addTarget(self, action: "buttonAction:", forControlEvents: UIControlEvents.TouchUpInside) 
    view.addSubview(button) 

} 

// Do this when the button is pressed 
func buttonAction (sender: UIButton) { 

    // Shrink the bar down to 0 width 
    UIView.animateWithDuration(3.0, 
     animations: ({ 

      self.countDownBar.frame = CGRectMake(self.countDownBar.frame.minX, self.countDownBar.frame.minY, 0, self.countDownBar.frame.height) 

     }), 
     completion: {finished in 

      // When finished, reset the bar to its original length 
      self.countDownBar.frame = CGRectMake(0, 0, 150, 15) 
      self.countDownBar.center = self.view.center 

      // Display if completed fully or interrupted 
      if finished { 
       print("animation finished") 
      } else { 
       print("animation interrupted") 
      } 
    }) 
} 

override func didReceiveMemoryWarning() { 
    super.didReceiveMemoryWarning() 
    // Dispose of any resources that can be recreated. 
} 

Answer 1

新usingSpringWithDamping动画调用设置选项AllowUserInteration能做到这一点，如果我正确理解你的问题。

animateWithDuration:delay:usingSpringWithDamping:initialSpringVelocity:options:animations:completion: 

此外，大厦可中断，并从这里的WWDC 2014的谈话响应交互会话：https://developer.apple.com/videos/wwdc/2014/可能是一个有用的资源（他们解释这是如何工作的更详细）。