Swift Infinite淡入和淡出循环

Question

如何在swift中产生类似于此的效果:

我希望动画永远循环.

Answer 1

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

请查看以下代码以了解实施情况.

代码:

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[UIViewAnimationOptions.AutoReverse, UIViewAnimationOptions.Repeat]在options参数中提供了一个数组.

这两个选项足以实现如下所示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UIViewAnimationOptions.AutoReverse从options参数中的数组中删除即可.你会得到这样的动画. https://s3.amazonaws.com/uploads.hipchat.com/37040/1764070/8fyRUlzqNHSQI47/noreverse.gif

Answer 2

对于iOS

让viewSquare你成为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)

Answer 3

我假设你正在为 iOS 编程。

尝试duration看看什么最适合您：

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)
    }
}