xcode Swift 无限淡入淡出循环

Swift Infinite Fade in and Out Loop

提问by Alex

How can I make a effect in swift similar to this:

我怎样才能在 swift 中产生与此类似的效果：

I want the animation to loop forever.

我希望动画永远循环播放。

回答by saugat gautam

For iOS

对于 iOS

UIViewAnimationOptions set provides different handy options to achieve a combination of beautiful and complex animations. For your particular scenario you will require two of the options.

UIViewAnimationOptions 集提供了不同的方便选项来实现漂亮和复杂动画的组合。对于您的特定场景，您将需要两个选项。

UIViewAnimationOptions.Repeat
UIViewAnimationOptions.AutoReverse

Check out the code below for implementation.

查看下面的代码以进行实现。

Code:

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)
    }

}

Explanation:I have created a view with a specific frame for demo purpose.

说明：为了演示目的，我创建了一个带有特定框架的视图。

The part you are interested in is the UIView.animateWithDurationmethod. Notice that I have provided an array [UIViewAnimationOptions.AutoReverse, UIViewAnimationOptions.Repeat]in the optionsparameter.

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。

These two options are enough to achieve a smooth and forever looping animation like below. https://s3.amazonaws.com/uploads.hipchat.com/37040/1764070/6Iow7n7WiWf6Naz/autoReverse.gif

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

If you don't want to reverse the animation, just remove UIViewAnimationOptions.AutoReversefrom the array in the optionsparameter. You will get an animation like this. https://s3.amazonaws.com/uploads.hipchat.com/37040/1764070/8fyRUlzqNHSQI47/noreverse.gif

如果不想反转动画，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

回答by Chanchal Raj

For iOS

对于 iOS

let viewSquarebe the name of the blue square in your question.

让viewSquare成为您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)

回答by Code Different

I assume you are programming for iOS.

我假设您正在为 iOS 编程。

Play around with the durationto see what suits you best:

试试看duration什么最适合你：

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)
    }
}

回答by Ahmed Safadi

Swift 5.1

斯威夫特 5.1

let duration = 0.5


func fadeIn(finished: Bool) {
    UIView.animate(withDuration: self.duration, delay: 0,
                   options: [.curveEaseInOut],
                   animations: { self.tftMap.alpha = 1 }, completion: self.fadeOut)
}

func fadeOut(finished: Bool) {
    UIView.animate(withDuration: self.duration, delay: 0,
                   options: [.curveEaseInOut],
                   animations: { self.tftMap.alpha = 0 }, completion: self.fadeIn)
}

回答by cs4alhaider

If you want repeatable fade animation you can do that by using CABasicAnimationlike below :

如果您想要可重复的淡入淡出动画，您可以使用CABasicAnimation如下方法：

First create handy UIView extension :

首先创建方便的 UIView 扩展：

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:

如何使用它：

    // 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)

回答by Bill

Swift 5

斯威夫特 5

This worked well for me. I wanted to animate a continuous fade in and out of a label, which I placed inside the "cardHeaderView" UIView.

这对我来说效果很好。我想为标签的连续淡入淡出设置动画，我将其放置在“cardHeaderView”UIView 中。

@IBOutlet weak var cardHeaderView: UIView!

Place this inside the "viewDidAppear". I went with a delay of zero so the animation would start right away.

把它放在“viewDidAppear”里面。我的延迟为零，所以动画会立即开始。

fadeViewInThenOut(view: cardHeaderView, delay: 0)

Here is the function.

这是功能。

func fadeViewInThenOut(view : UIView, delay: TimeInterval) {

    let animationDuration = 1.5

    UIView.animate(withDuration: animationDuration, delay: delay, options: [UIView.AnimationOptions.autoreverse, UIView.AnimationOptions.repeat], animations: {
        view.alpha = 0
    }, completion: nil)

}