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。