UIImageView 没有动画

Question

I am trying to have a view in which 3 dots would animate infinity and here is the code snippet(swift 5) for it

func showAnimatingDotsInImageView() {
        let lay = CAReplicatorLayer()
        lay.frame = CGRect(x: 0, y: 0, width: 15, height: 7) //yPos == 12
        let circle = CALayer()
        circle.frame = CGRect(x: 0, y: 0, width: 7, height: 7)
        circle.cornerRadius = circle.frame.width / 2
        circle.backgroundColor = UIColor.green.cgColor
        lay.addSublayer(circle)
        lay.instanceCount = 3
        lay.instanceTransform = CATransform3DMakeTranslation(10, 0, 0)
        let anim = CABasicAnimation(keyPath: #keyPath(CALayer.opacity))
        anim.fromValue = 1.0
        anim.toValue = 0.2
        anim.duration = 1
        anim.repeatCount = .infinity
        circle.add(anim, forKey: nil)
        lay.instanceDelay = anim.duration / Double(lay.instanceCount)
        test1.layer.addSublayer(lay)
    }

In the above code test1 is a UIImageView. The main issue is the dots are shown but it's static and doesn't animate.

Answer 1

I tried your code and it is animating just fine. Any chance you are calling this from a thread which is different than the Main thread? Like for example something on the background is happening, which you want to triggers the loading?

Try adding:

DispatchQueue.main.async { [weak self] in
    self?.showAnimatingDotsInImageView()
}