func animation1(layerParam: CAShapeLayer){
let animation = CABasicAnimation(keyPath: "strokeStart")
animation.fromValue = 0
animation.toValue = 1
animation.duration = 2.0
layerParam.addAnimation(animation, forKey: "")
}
这段代码可以用来实现曲线的绘制动画，fromValue和toValue分别表示动画起始点和终点，0代表startPoint，1代表endPoint，整条路径可以看成单位1，0.5之类的中间值也是可以的。别忘了把函数添加
self.animation1(layer)
忽略那个鼠标吧。。。。。。
还可以写成中间向两边的效果
func animation2(layerParam: CAShapeLayer){
layerParam.strokeStart = 0.5
layerParam.strokeEnd = 0.5
let animation1 = CABasicAnimation(keyPath: "strokeStart")
animation1.fromValue = 0.5
animation1.toValue = 0
animation1.duration = 2
let animation2 = CABasicAnimation(keyPath: "strokeEnd")
animation2.fromValue = 0.5
animation2.toValue = 1
animation2.duration = 2
layerParam.addAnimation(animation1, forKey: "")
layerParam.addAnimation(animation2, forKey: "")
}
配合lineWidth可以得到下面效果
func animation3(layerParam: CAShapeLayer){
let animation = CABasicAnimation(keyPath: "lineWidth")
animation.fromValue = 1
animation.toValue = 10
animation.duration = 2
layerParam.addAnimation(animation, forKey: "")
}
圆形矩形什么都可以实现。
原文：http://www.cnblogs.com/ybw123321/p/5210707.html