画线动画

Question

我希望在屏幕中央有一条线,并像蛇一样动画

这是我想要制作的一步一步的动画

我怎样才能做到这一点？

Answer 1

您可以动画的行程结束path上CAShapeLayer,例如,

weak var shapeLayer: CAShapeLayer?

@IBAction func didTapButton(_ sender: Any) {
    // remove old shape layer if any

    self.shapeLayer?.removeFromSuperlayer()

    // create whatever path you want

    let path = UIBezierPath()
    path.move(to: CGPoint(x: 10, y: 50))
    path.addLine(to: CGPoint(x: 200, y: 50))
    path.addLine(to: CGPoint(x: 200, y: 240))

    // create shape layer for that path

    let shapeLayer = CAShapeLayer()
    shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
    shapeLayer.strokeColor = #colorLiteral(red: 1, green: 0, blue: 0, alpha: 1).cgColor
    shapeLayer.lineWidth = 4
    shapeLayer.path = path.cgPath

    // animate it

    view.layer.addSublayer(shapeLayer)
    let animation = CABasicAnimation(keyPath: "strokeEnd")
    animation.fromValue = 0
    animation.duration = 2
    shapeLayer.add(animation, forKey: "MyAnimation")

    // save shape layer

    self.shapeLayer = shapeLayer
}

产量:

显然,您可以将其更改UIBezierPath为符合您兴趣的任何内容.例如,您可以在路径中包含空格.或者您甚至不需要具有直线路径:

let path = UIBezierPath()
path.move(to: CGPoint(x: 10, y: 130))
path.addCurve(to: CGPoint(x: 210, y: 200), controlPoint1: CGPoint(x: 50, y: -100), controlPoint2: CGPoint(x: 100, y: 350))

您还可以在以下位置组合笔划开始和结束的动画CAAnimationGroup:

// create shape layer for that path (this defines what the path looks like when the animation is done)

let shapeLayer = CAShapeLayer()
shapeLayer.fillColor = #colorLiteral(red: 0, green: 0, blue: 0, alpha: 0).cgColor
shapeLayer.strokeColor = #colorLiteral(red: 1, green: 0, blue: 0, alpha: 1).cgColor
shapeLayer.lineWidth = 5
shapeLayer.path = path.cgPath
shapeLayer.strokeStart = 0.8

let startAnimation = CABasicAnimation(keyPath: "strokeStart")
startAnimation.fromValue = 0
startAnimation.toValue = 0.8

let endAnimation = CABasicAnimation(keyPath: "strokeEnd")
endAnimation.fromValue = 0.2
endAnimation.toValue = 1.0

let animation = CAAnimationGroup()
animation.animations = [startAnimation, endAnimation]
animation.duration = 2
shapeLayer.add(animation, forKey: "MyAnimation")

产量:

CoreAnimation为您提供了对描边路径呈现方式的大量控制.