中断animateWithDuration

Question

我有一个倒计时的动画计时器条，我希望能够取消动画，并在满足特定条件时重置该计时器条，这样它就不会一直到0。类似地，如果它真的变成了0，我想调用一个函数。

现在，我只连接了一个按钮进行测试。再次按下按钮确实可以防止它一直向下，但它会跳过屏幕，并且完成块中的print语句总是返回true。我认为多个动画相互堆叠在一起。

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

如果我正确理解了您的问题，那么在新的usingSpringWithDamping动画调用中将选项设置为AllowUserInteration可以做到这一点。

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

此外，WWDC2014演讲中关于构建可中断和响应式交互的会议：https://developer.apple.com/videos/wwdc/2014/可能是一个有用的资源(他们更详细地解释了这是如何工作的)。