非常基本的 Swift 动画答案

【问题标题】：Very Basic Swift Animation非常基本的 Swift 动画
【发布时间】：2015-08-14 22:22:56
【问题描述】：

我正在尝试将视图从情节提要上的位置向上移动 100 像素。

如果随机生成的数字为 1，则标签变为未中奖。

如果随机生成的数字是 2，则标签会更改为他们中奖了。

我正在使用以下代码：

 override func motionEnded(motion: UIEventSubtype,
    withEvent event: UIEvent?) {

        if motion == .MotionShake{

           let randomNumber = arc4random_uniform(2) + 1

            print(randomNumber)

            if randomNumber == 1 {

                labelOne.text = "Sorry!"
                labelTwo.text = "You Have Not Won This Time"
                labelThree.text = "Better Luck Tomorrow"

            }

            if randomNumber == 2 {

                labelOne.text = "Winner!"
                labelTwo.text = "1 x Shot Patron Cafe"
                labelThree.text = "Show at the bar to claim."

            }

            let xPosition = stampView.frame.origin.x

            //View will slide 20px up
            let yPosition = stampView.frame.origin.y - 100

            let height = stampView.frame.size.height
            let width = stampView.frame.size.width

            UIView.animateWithDuration(3.0, animations: {

                self.stampView.frame = CGRectMake(xPosition, yPosition, height, width)


            })


            print("SHAKEN!")

        }

}

我发现有时当我摇动设备时，动画会从原始位置下方 100px 开始并移回原位，而其他时候它会从最后一个位置向上移动 100px。

如何确保它始终从故事板上的原始位置移动？

【问题讨论】：

你在使用自动布局吗？
嗨，不，我发现如果我将文本更改移出功能，它似乎工作得非常愉快。不知道为什么！
可能在后台线程上执行了“motionEnded”。尝试将您的代码包装在主队列中。
让我知道这是否有效。

标签： ios swift animation

【解决方案1】：

确保某物留在同一位置的最佳方法是在您的Main.storyboard 文件中对其进行约束（首先要做的事情）。另外，作为额外的预防措施，您可以在viewDidLoad 中读取其帧值，然后在motionEnded 中再次设置。

var stampFrame : CGRect = CGRect(x: 0, y: 0, width: 0, height: 0) // This is stampFrame's initial value before being set in viewDidLoad

override func viewDidLoad() {
    super.viewDidLoad()
    stampFrame = stampView.frame // Here we store the frame value for usage later
    // If you would like, you can also set this in a method like viewWillAppear or viewDidAppear, but I'd just keep it in viewDidLoad
}


override func motionEnded(motion: UIEventSubtype, withEvent event: UIEvent?) {

    stampView.frame = stampFrame 

    if motion == .MotionShake{

       let randomNumber = arc4random_uniform(2) + 1

        print(randomNumber)

        if randomNumber == 1 {

            labelOne.text = "Sorry!"
            labelTwo.text = "You Have Not Won This Time"
            labelThree.text = "Better Luck Tomorrow"

        }

        if randomNumber == 2 {

            labelOne.text = "Winner!"
            labelTwo.text = "1 x Shot Patron Cafe"
            labelThree.text = "Show at the bar to claim."

        }

     //   let xPosition = stampView.frame.origin.x

     //   View will slide 20px up
     //   let yPosition = stampView.frame.origin.y - 100

     //   let height = stampView.frame.size.height
     //   let width = stampView.frame.size.width
     // The code above is redundant, we can just do it all in the UIView.animate 

        UIView.animate(withDuration: 3.0, animations: {

            self.stampView.frame.origin.y -= 100
     // This moves stampView's position up 100pts from its current location


        })


        print("SHAKEN!")

    }

无论如何，我希望对您有所帮助，如果您还有其他问题，欢迎您提出。

【讨论】：