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

1. - (void)viewDidLoad
2. {
3. [super viewDidLoad];
4. //create a path
5. UIBezierPath *bezierPath = [[UIBezierPath alloc] init];
6. [bezierPath moveToPoint:CGPointMake(0, 150)];
7. [bezierPath addCurveToPoint:CGPointMake(300, 150) controlPoint1:CGPointMake(75, 0) controlPoint2:CGPointMake(225, 300)];
8. //draw the path using a CAShapeLayer
9. CAShapeLayer *pathLayer = [CAShapeLayer layer];
10. pathLayer.path = bezierPath.CGPath;
11. pathLayer.fillColor = [UIColor clearColor].CGColor;
12. pathLayer.strokeColor = [UIColor redColor].CGColor;
13. pathLayer.lineWidth = 3.0f;
14. [self.containerView.layer addSublayer:pathLayer];
15. //add a colored layer
16. CALayer *colorLayer = [CALayer layer];
17. colorLayer.frame = CGRectMake(0, 0, 64, 64);
18. colorLayer.position = CGPointMake(0, 150);
19. colorLayer.backgroundColor = [UIColor greenColor].CGColor;
20. [self.containerView.layer addSublayer:colorLayer];
21. //create the position animation
22. CAKeyframeAnimation *animation1 = [CAKeyframeAnimation animation];
23. animation1.keyPath = @"position";
24. animation1.path = bezierPath.CGPath;
25. animation1.rotationMode = kCAAnimationRotateAuto;
26. //create the color animation
27. CABasicAnimation *animation2 = [CABasicAnimation animation];
28. animation2.keyPath = @"backgroundColor";
29. animation2.toValue = (__bridge id)[UIColor redColor].CGColor;
30. //create group animation
31. CAAnimationGroup *groupAnimation = [CAAnimationGroup animation];
32. groupAnimation.animations = @[animation1, animation2];
33. groupAnimation.duration = 4.0;
34. //add the animation to the color layer
35. [colorLayer addAnimation:groupAnimation forKey:nil];
36. }

图8.3 关键帧路径和基础动画的组合