CAShapeLayer path spring animation not 'overshooting'

问题

I'm experimenting with animating CAShapeLayer paths with CASpringAnimation. The expected result is a 'morphing' between shapes that acts 'springy'.

I have a basic code example between a circle and square path as below, however the end result is a spring animation that does not 'overshoot' past the final, larger square path, which is the expected behaviour.

My code is:

let springAnimation = CASpringAnimation(keyPath: "path")
springAnimation.damping = 1
springAnimation.duration = springAnimation.settlingDuration
springAnimation.fromValue = standardCirclePath().cgPath
springAnimation.toValue = standardSquarePath().cgPath

circleLayer.add(springAnimation, forKey: nil) // Where circleLayer (red background) is a sublayer of a basic UIView in the frame (blue background)

I got my paths from this answer.

Is there a way with CASpringAnimation to achieve this for a CAShapeLayer path transform? Otherwise, what are the alternatives?

回答1:

Hello I had been working on your question and this is my results, the glitches on the gif is because my gif converter is very bad converter

this is the code

class ViewController: UIViewController {

    @IBOutlet weak var animatableVIew: UIView!
    var isBall = false
    override func viewDidLoad() {
        super.viewDidLoad()
        // Do any additional setup after loading the view, typically from a nib.
    }
    @IBAction func startAnimation(sender: AnyObject) {

        isBall = !isBall

        let springAnimation = CASpringAnimation(keyPath: "cornerRadius")
        let halfWidth = animatableVIew.frame.width / 2
        let cornerRadius: CGFloat = isBall ? halfWidth : 0
        springAnimation.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionEaseIn)
        springAnimation.fromValue = isBall ? 0 : halfWidth ;
        springAnimation.toValue = cornerRadius;
        springAnimation.damping = 7
        springAnimation.duration = springAnimation.settlingDuration
        animatableVIew.layer.cornerRadius = cornerRadius

        let springAnimation2 = CAKeyframeAnimation(keyPath: "transform.scale")
        springAnimation2.timingFunction = CAMediaTimingFunction(name: kCAMediaTimingFunctionLinear)
        springAnimation2.values = [1,0.9,1.4,0.8,1]
        springAnimation2.keyTimes = [ 0, (1 / 6.0), (3 / 6.0), (5 / 6.0), 1 ];
        springAnimation2.duration = springAnimation.settlingDuration * 0.5

        let groupSpringAnimation = CAAnimationGroup()
        groupSpringAnimation.animations = [springAnimation,springAnimation2]
        groupSpringAnimation.duration = springAnimation.settlingDuration
        groupSpringAnimation.beginTime = 0;
        animatableVIew.layer.addAnimation(groupSpringAnimation, forKey: "group")

    }

    override func didReceiveMemoryWarning() {
        super.didReceiveMemoryWarning()
        // Dispose of any resources that can be recreated.
    }


}

I hope this helps you

来源：https://stackoverflow.com/questions/38464864/cashapelayer-path-spring-animation-not-overshooting

标签

ios

Spring

animation

core-animation

cashapelayer