8.2 动画组

# 动画组 `CABasicAnimation`和`CAKeyframeAnimation`仅仅作用于单独的属性，而`CAAnimationGroup`可以把这些动画组合在一起。`CAAnimationGroup`是另一个继承于`CAAnimation`的子类，它添加了一个`animations`数组的属性，用来组合别的动画。我们把清单8.6那种关键帧动画和调整图层背景色的基础动画组合起来（清单8.10），结果如图8.3所示。 清单8.10 组合关键帧动画和基础动画 ~~~ - (void)viewDidLoad { [super viewDidLoad]; //create a path UIBezierPath *bezierPath = [[UIBezierPath alloc] init]; [bezierPath moveToPoint:CGPointMake(0, 150)]; [bezierPath addCurveToPoint:CGPointMake(300, 150) controlPoint1:CGPointMake(75, 0) controlPoint2:CGPointMake(225, 300)]; //draw the path using a CAShapeLayer CAShapeLayer *pathLayer = [CAShapeLayer layer]; pathLayer.path = bezierPath.CGPath; pathLayer.fillColor = [UIColor clearColor].CGColor; pathLayer.strokeColor = [UIColor redColor].CGColor; pathLayer.lineWidth = 3.0f; [self.containerView.layer addSublayer:pathLayer]; //add a colored layer CALayer *colorLayer = [CALayer layer]; colorLayer.frame = CGRectMake(0, 0, 64, 64); colorLayer.position = CGPointMake(0, 150); colorLayer.backgroundColor = [UIColor greenColor].CGColor; [self.containerView.layer addSublayer:colorLayer]; //create the position animation CAKeyframeAnimation *animation1 = [CAKeyframeAnimation animation]; animation1.keyPath = @"position"; animation1.path = bezierPath.CGPath; animation1.rotationMode = kCAAnimationRotateAuto; //create the color animation CABasicAnimation *animation2 = [CABasicAnimation animation]; animation2.keyPath = @"backgroundColor"; animation2.toValue = (__bridge id)[UIColor redColor].CGColor; //create group animation CAAnimationGroup *groupAnimation = [CAAnimationGroup animation]; groupAnimation.animations = @[animation1, animation2]; groupAnimation.duration = 4.0; //add the animation to the color layer [colorLayer addAnimation:groupAnimation forKey:nil]; } ~~~  图8.3 关键帧路径和基础动画的组合