我如何得到这个动画渐变工作？ [英] How do I get this fade animation to work?

问题描述

我想建立一个简单的脉动环，将突出一个按钮，以提示用户推荐的选择。我做了简单的淡入（）和淡出（）函数，设置在淡出（）的延迟，因此它会触发为淡入（）完成......或者至少这是我的本意。什么样的结果是，当按钮pressed，环瞬间变为阿尔法= 1，然后2秒的延迟，然后褪色超过2秒。有一次，我有一个周期的工作，我希望把它变成一个循环继续下去，而需要的。

I'm trying to set up a simple pulsating ring that will highlight a button, to prompt the user to the recommended choice. I made simple fadeIn() and fadeOut() functions, set a delay in the fadeOut(), so that it will trigger as the fadeIn() completes...or at least that's what I intended. What results is, when the button is pressed, the ring instantly goes to alpha = 1, then delays for 2 seconds, and then fades over 2 seconds. Once I have a cycle working, I'd like to put it into a loop to keep it going while needed.

如预期，如果单独执行的功能，要么将工作。我发现另一个线程，与简单的淡入淡出或交易，但不能同时在一起。

Either function will work as intended, if executed alone. I found another thread that deals with simple fadeIn or fadeOut, but not both together.

我敢肯定，code是做什么我告诉它做什么，但我不明白，为什么它不工作。有人能指出我的错误呢？谢谢。

I'm sure the code is doing exactly what I'm telling it do, but I can't figure out why it's not working. Can someone point to my mistake? Thanks.

@IBOutlet weak var greenRing: UIImageView!

@IBAction func buttonPressed(sender: AnyObject)

    {
        fadeIn()

        fadeOut()
    }

func fadeIn() {

    UIImageView.animateWithDuration(2.0, animations: {

        self.greenRing.alpha = 1

        })

}

func fadeOut() {

    UIImageView.animateWithDuration(2.0, delay: 2.0, options: nil, animations: {

        self.greenRing.alpha = 0

        }, completion: nil)

}

override func viewDidLoad() {
    super.viewDidLoad()

    greenRing.alpha = 0

}

}

推荐答案

可以实现与一个重复的动画你想要的效果。通 .Autoreverse | .Repeat 为选项：到 animateWithDuration ，它会自动反转并重复淡入

You can achieve your desired effect with one repeating animation. Pass .Autoreverse | .Repeat as the options: to animateWithDuration and it will automatically reverse and repeat the fadeIn.

当按钮被pressed，您可以通过调用 greenRing.layer.removeAllAnimations（）

When the button is pressed, you can stop the animation by calling greenRing.layer.removeAllAnimations()

动画也可能会看起来更好，如果你还添加选项 UIViewAnimationOption.CurveEaseInOut 。所以：

The animation will also likely look nicer if you also add the option UIViewAnimationOption.CurveEaseInOut. So:

.Autoreverse | .Repeat | .CurveEaseInOut

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