Swift Infinite淡入和淡出循环

Posted 2021-04-13

我怎样才能在类似于此的快速效果：

我希望动画永远循环。

答案

对于ios

UIViewAnimationOptions集提供了不同的方便选项，以实现美观和复杂动画的组合。对于您的特定情况，您将需要两个选项。

UIViewAnimationOptions.Repeat
UIViewAnimationOptions.AutoReverse

查看下面的代码以实现。

码：

class MyViewController: UIViewController {

    override func viewDidLoad() {
        super.viewDidLoad()

        let view = UIView(frame: CGRect(x: 0, y: 0, width: 200, height: 200))
        view.backgroundColor = UIColor.blueColor()
        self.view.addSubview(view)

        UIView.animateWithDuration(1, 
        delay: 0, 
        options: [UIViewAnimationOptions.Autoreverse, UIViewAnimationOptions.Repeat], 
        animations: {
              view.backgroundColor = UIColor.clearColor()
          }, 
        completion: nil)
    }

}

说明：我创建了一个具有特定框架的视图用于演示目的。

您感兴趣的部分是UIView.animateWithDuration方法。请注意，我在[UIViewAnimationOptions.AutoReverse, UIViewAnimationOptions.Repeat]参数中提供了一个数组options。

这两个选项足以实现如下所述的平滑且永久循环的动画。 https://s3.amazonaws.com/uploads.hipchat.com/37040/1764070/6Iow7n7WiWf6Naz/autoReverse.gif

如果您不想反转动画，只需从UIViewAnimationOptions.AutoReverse参数中的数组中删除options即可。你会得到这样的动画。 https://s3.amazonaws.com/uploads.hipchat.com/37040/1764070/8fyRUlzqNHSQI47/noreverse.gif

另一答案

对于iOS

让viewSquare成为你问题中蓝色方块的名称。

UIView.animate(withDuration: 0.5, delay: 0, options: [.repeat,.autoreverse], animations: {
            viewSquare.alpha = 0.0
        }, completion: nil)

另一答案

我假设您正在为iOS编程。

和duration一起玩，看看最适合你的是什么：

class ViewController: UIViewController {
    @IBOutlet weak var myView: UIView!
    let duration = 0.5

    override func viewDidLoad() {
        super.viewDidLoad()
        self.fadeOut(true)
    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
    }

    func fadeIn(finished: Bool) {
        UIView.animateWithDuration(self.duration, delay: 0, options: [.CurveEaseInOut], animations: { self.myView.alpha = 1 } , completion: self.fadeOut)
    }

    func fadeOut(finished: Bool) {
        UIView.animateWithDuration(self.duration, delay: 0, options: [.CurveEaseInOut], animations: { self.myView.alpha = 0 } , completion: self.fadeIn)
    }
}

另一答案

如果你想要可重复的淡入淡出动画你可以通过使用如下的CABasicAnimation来做到这一点：

First create handy UIView extension :

extension UIView {

    enum AnimationKeyPath: String {
        case opacity = "opacity"
    }

    func flash(animation: AnimationKeyPath ,withDuration duration: TimeInterval = 0.5, repeatCount: Float = 5){
        let flash = CABasicAnimation(keyPath:.opacity.rawValue)
        flash.duration = duration
        flash.fromValue = 1 // alpha
        flash.toValue = 0 // alpha
        flash.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseInEaseOut)
        flash.autoreverses = true
        flash.repeatCount = repeatCount

        layer.add(flash, forKey: nil)
    }
}

How to use it:

    // You can use it with all kind of UIViews e.g. UIButton, UILabel, UIImage, UIImageView, ...
    imageView.flash(animation: .opacity, withDuration: 1, repeatCount: 5)
    titleLabel.flash(animation: .opacity, withDuration: 1, repeatCount: 5)