IOS Animation-CAShapeLayer、UIBezierPath与Animation的结合

在阅读本文之前，对CAShapeLayer、UIBezierPath不熟悉的话，可以先阅读文章 贝塞尔曲线与Layer

如果对动画不熟悉的话，先阅读文章 动画基础、深入

Layer是绘图的画板，Bezier是画图的画笔，Animation是画图的动作。现在我们可以通过下面例子更好的让它们更好地结合在一起。

1）画一个小屋子动画

我们首先通过定义CAShapeLayer画板，然后定义path来确定画图路径。最后使用动画。如下面代码

 1     //让一个屋子的线画起来的动画效果
 2     func addCAShapeLayerAnimationStrokeEnd() {
 3         //创建CAShapeLayer，屋子的layer
 4         let slayer = CAShapeLayer.init()
 5         slayer.strokeColor = UIColor.blackColor().CGColor
 6         slayer.fillColor = UIColor.clearColor().CGColor
 7
 8         //创建屋子的路径path
 9         let path = UIBezierPath.init()
10         path.moveToPoint(CGPointMake(20, 300))
11         path.addLineToPoint(CGPointMake(20, 100))
12         path.addLineToPoint(CGPointMake(120, 50))
13         path.addLineToPoint(CGPointMake(220, 100))
14         path.addLineToPoint(CGPointMake(220, 300))
15         path.addLineToPoint(CGPointMake(20, 300))
16
17         //把画图的路径path添加到layer中
18         slayer.path = path.CGPath
19         //添加slayer到view.layer
20         self.view.layer.addSublayer(slayer)
21
22         //创建动画，strokeEnd。让线画起来的效果
23         let ani = CABasicAnimation(keyPath: "strokeEnd")
24         ani.fromValue = 0
25         ani.toValue = 1
26         ani.repeatCount = 1
27         ani.duration = 3
28
29         slayer.addAnimation(ani, forKey: "addCAShapeLayerAnimationStrokeEnd")
30     }

2）小屋子+画笔的动画

上面1）中我们画了一个屋子的动画，那么如果我们想在屋子上面添加一个画笔来画，让动画更加生动。所以我们用到keyframe动画来添加path。

 1     //让一个屋子的线画起来的动画效果
 2     func addCAShapeLayerAnimationStrokeEnd2() {
 3         //---创建CAShapeLayer，屋子的layer start---
 4         let pathLayer = CAShapeLayer.init()
 5         pathLayer.strokeColor = UIColor.blackColor().CGColor
 6         pathLayer.fillColor = UIColor.clearColor().CGColor
 7         //创建屋子的路径path
 8         let path = UIBezierPath.init()
 9         path.moveToPoint(CGPointMake(20, 300))
10         path.addLineToPoint(CGPointMake(20, 100))
11         path.addLineToPoint(CGPointMake(120, 50))
12         path.addLineToPoint(CGPointMake(220, 100))
13         path.addLineToPoint(CGPointMake(220, 300))
14         path.addLineToPoint(CGPointMake(20, 300))
15         //把画图的路径path添加到layer中
16         pathLayer.path = path.CGPath
17         //添加slayer到view.layer
18         self.view.layer.addSublayer(pathLayer)
19         //---创建CAShapeLayer，屋子的layer end---
20
21         //---创建画笔layer start---
22         let panLayer = CALayer.init()
23         panLayer.anchorPoint = CGPointZero
24         panLayer.frame = CGRectMake(0, 0, 30, 30)
25         panLayer.contents = UIImage(named: "pan.png")?.CGImage
26         self.view.layer.addSublayer(panLayer)
27         //---创建画笔layer end---
28
29         //---创建动画，strokeEnd。让线画起来的效果 start---
30         let strokeEndAnimation = CABasicAnimation(keyPath: "strokeEnd")
31         strokeEndAnimation.fromValue = 0
32         strokeEndAnimation.toValue = 1
33         strokeEndAnimation.repeatCount = 100
34         strokeEndAnimation.duration = 3
35         pathLayer.addAnimation(strokeEndAnimation, forKey: "strokeEndAnimation")
36         //---创建动画，strokeEnd。让线画起来的效果 end---
37
38         //---让画笔动起来动画start---
39         let panAnimation = CAKeyframeAnimation(keyPath: "position")
40         panAnimation.path = path.CGPath
41         panAnimation.calculationMode = kCAAnimationPaced
42         panAnimation.duration = 3
43         panAnimation.repeatCount = 100
44         panLayer.addAnimation(panAnimation, forKey: "panAnimation")
45         //---让画笔动起来动画end---
46
47     }