CAAnimationGroup
单一的动画并不能满足某些特定需求，这时就需要用到动画组，使得多个动画并发执行。如果了解过一些核心动画的基础知识，动画组就再简单不过了，不太熟悉的话请点击：CAAnimation基础。
CAAnimationGroup继承于CAAnimation，独有属性：public var animations: [CAAnimation]?，一个CAAnimation对象的数组。
接下来，来看几组简单的CAAnimationGroup使用方法：
- 旋转+平移
-
效果图：
代码：
//创建图层
let wheelLayer = CALayer()
let wheel = UIImage(named: "车轮-(1)")!
wheelLayer.contents = wheel.CGImage
wheelLayer.frame = CGRect(x: 0.0, y: 667 / 2, width:wheel.size.width, height: wheel.size.height)
view.layer.addSublayer(wheelLayer)
//旋转动画
let rollAnimation = CABasicAnimation(keyPath: "transform.rotation")
rollAnimation.toValue = M_PI * 2
//平移动画
let translateAnimation = CABasicAnimation(keyPath: "transform.translation.x")
translateAnimation.toValue = 375
//动画组
let animationGroup = CAAnimationGroup()
animationGroup.duration = 2
animationGroup.animations = [rollAnimation, translateAnimation]
animationGroup.repeatCount = 1_000_000
wheelLayer.addAnimation(animationGroup, forKey: nil)
- 缩放+透明度
-
效果图：
代码：
//创建图层
let layer = CALayer()
let symbol = UIImage(named: "+")!
layer.contents = symbol.CGImage
layer.frame = CGRect(x: (375 - symbol.size.width) / 2, y: (667 - symbol.size.height) / 2, width: symbol.size.width, height: symbol.size.height)
view.layer.addSublayer(layer)
//缩放动画
let scaleAnimation = CABasicAnimation(keyPath: "transform.scale")
scaleAnimation.fromValue = 0.0
scaleAnimation.toValue = 10.0
//透明度动画
let opacityAnimation = CABasicAnimation(keyPath: "opacity")
opacityAnimation.toValue = 0.0
//动画组
let animationGroup = CAAnimationGroup()
animationGroup.animations = [scaleAnimation, opacityAnimation]
animationGroup.duration = 2.0
animationGroup.removedOnCompletion = false
animationGroup.fillMode = kCAFillModeForwards
animationGroup.repeatCount = MAXFLOAT
layer.addAnimation(animationGroup, forKey: nil)
- BezierPath+旋转
-
效果图：
代码：
//创建图层
let layer = CALayer()
let satellite = UIImage(named: "NoNetwork")!
layer.contents = satellite.CGImage
let centerY = (667 - satellite.size.height) / 2
layer.frame = CGRect(x: 0, y: centerY, width: satellite.size.width, height: satellite.size.height)
view.layer.addSublayer(layer)
//创建贝塞尔曲线
let bezierPath = UIBezierPath()
bezierPath.moveToPoint(CGPoint(x: 0, y: centerY))
bezierPath.addQuadCurveToPoint(CGPoint(x: 375, y: centerY), controlPoint: CGPoint(x: 375/2, y: 0))
//创建shapeLayer划线（后面会有单独的章节介绍）
let shapeLayer = CAShapeLayer()
shapeLayer.path = bezierPath.CGPath
shapeLayer.fillColor = UIColor.clearColor().CGColor
shapeLayer.strokeColor = UIColor.whiteColor().CGColor
view.layer.addSublayer(shapeLayer)
//旋转动画
let rotateAnimation = CABasicAnimation(keyPath: "transform.rotation.x")
rotateAnimation.toValue = M_PI * 2
rotateAnimation.duration = 1.0
rotateAnimation.repeatCount = MAXFLOAT
//BezierPath动画
let bezierAnimation = CAKeyframeAnimation(keyPath: "position")
bezierAnimation.path = bezierPath.CGPath
//动画组
let animationGroup = CAAnimationGroup()
animationGroup.animations = [rotateAnimation, bezierAnimation]
animationGroup.duration = 5.0
animationGroup.repeatCount = MAXFLOAT
animationGroup.autoreverses = true
layer.addAnimation(animationGroup, forKey: nil)
结语
以上几个例子，简单的介绍了CAAnimationGroup的使用方法，若有疑问或需要Demo请留言。
