動畫組

CABasicAnimation和CAKeyframeAnimation僅僅作用於單獨的屬性，而CAAnimationGroup可以把這些動畫組合在一起。CAAnimationGroup是另一個繼承於CAAnimation的子類，它添加了一個animations數組的屬性，用來組合別的動畫。我們把清單8.6那種關鍵幀動畫和調整圖層背景色的基礎動畫組合起來（清單8.10），結果如圖8.3所示。

清單8.10 組合關鍵幀動畫和基礎動畫

 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 }

動畫組(顯示動畫)