我在这个简单的线条动画中有点挣扎。我想出了如何暂停它,但我需要的是能够从调用函数resetAnimation()的那一刻起就将动画反向还原到起点。
let pathAnimation = CABasicAnimation(keyPath: "strokeEnd")
let pathLayer = CAShapeLayer()
func lineAnimation() {
let path = UIBezierPath()
let screenWidth = self.view.bounds.width
let screenHeight = self.view.bounds.height
path.moveToPoint(CGPointMake(screenWidth, screenHeight / 2))
path.addLineToPoint(CGPointMake(screenWidth - screenWidth, screenHeight / 2))
self.pathLayer.frame = self.view.bounds
self.pathLayer.path = path.CGPath
self.pathLayer.strokeColor = UIColor.whiteColor().CGColor
self.pathLayer.fillColor = nil
self.pathLayer.lineWidth = 3.0
self.pathLayer.lineCap = kCALineCapRound
self.pathLayer.speed = 1
self.view.layer.addSublayer(pathLayer)
self.pathAnimation.duration = 5.0
self.pathAnimation.fromValue = 0.0
self.pathAnimation.toValue = 1.0
pathLayer.addAnimation(pathAnimation, forKey: "animate")
}
func pauseAnimation() {
let pausedTime = pathLayer.convertTime(CACurrentMediaTime(), fromLayer: nil)
pathLayer.speed = 0
pathLayer.timeOffset = pausedTime
}
func resetAnimation() {
}
您只需要创建一个新动画并删除旧动画即可。新动画的起点将是表示层中该属性的当前值。我还建议将形状图层的框架设置为实际贝塞尔曲线形状的边界,而不是整个视图的边界-当您开始四处移动和缩放/旋转/等操作时,这是一个好习惯。否则,您将面临大量时髦的转换或锚点更改。
这是我要做的:
let pathLayer = CAShapeLayer()
// first, separate your drawing code from your animation code.
// this way you can call animations without instantiating new objects
func drawLine() {
let path = UIBezierPath()
// draw your path with no position translation.. move the layer
path.moveToPoint(CGPointMake(view.bounds.width, 0))
path.addLineToPoint(CGPointMake(0, 0))
pathLayer.frame = path.bounds
// this line sets the position of the layer appropriately
pathLayer.position = view.bounds.width - pathLayer.bounds.width / 2
pathLayer.path = path.CGPath
pathLayer.strokeColor = UIColor.whiteColor().CGColor
pathLayer.fillColor = nil
pathLayer.lineWidth = 3.0
pathLayer.lineCap = kCALineCapRound
view.layer.addSublayer(pathLayer)
}
func lineAnimation() {
let pathAnimation = CABasicAnimation(keyPath: "strokeEnd")
pathAnimation.duration = 5.0
pathAnimation.fromValue = 0.0
pathAnimation.toValue = 1.0
pathLayer.addAnimation(pathAnimation, forKey: "strokeEnd")
}
func reverseAnimation() {
let revAnimation = CABasicAnimation(keyPath: "strokeEnd")
revAnimation.duration = 5.0
// every Core Animation has a 'presentation layer' that contains the animated changes
revAnimation.fromValue = pathLayer.presentationLayer()?.strokeEnd
revAnimation.toValue = 0.0
pathLayer.removeAllAnimations()
pathLayer.addAnimation(revAnimation, forKey: "strokeEnd")
}
请记住,您还需要设置属性,以便保留动画的最终值。
您也可以使用autoreverses
协议的CAMediaTiming
协议的CABasicAnimation
属性>