项目介绍：

WMCAAnimationGroup

最近研究了一下CAAnimationGroup 组动画,觉得很有意思 ,写了这个呆萌 ,大家一起探讨好玩的动画吧

2017/01/8 关于layer 动画组的一些探讨

这两天视觉这边要求做了个动画:事物在下降一定高度后,先放大,后变小,同时背后的背景开始旋转闪烁;

这里主要用到了layer动画 , CAAnimationGroup 组合动画 和CABasicAnimation 来实现

pragma mark – 开始动画

主要的代码如下
‘
-(void) showAnimation {

self.gifImageView.hidden = NO;
self.bgImageView.hidden = NO;
//组动画+基本动画
CABasicAnimation* moveAnimation = [[CABasicAnimation alloc] init];
moveAnimation.keyPath = @"position";
moveAnimation.beginTime =  0.0;
moveAnimation.fromValue = [NSValue valueWithCGPoint:CGPointMake([UIScreen mainScreen].bounds.size.width*0.5, 0)];
moveAnimation.toValue = [NSValue valueWithCGPoint:CGPointMake([UIScreen mainScreen].bounds.size.width*0.5, CurrentHeight * 0.5 - 80)];
    moveAnimation.duration = 0.5;
moveAnimation.repeatCount = 1;
moveAnimation.removedOnCompletion = NO;
moveAnimation.fillMode = kCAFillModeForwards;

//放大图片动画
CABasicAnimation* enlargeAnimation = [[CABasicAnimation alloc] init];
enlargeAnimation.keyPath = @"transform.scale";
enlargeAnimation.beginTime = 0.4;
enlargeAnimation.byValue = [NSNumber numberWithFloat:1];
enlargeAnimation.toValue = [NSNumber numberWithFloat:1.8];
enlargeAnimation.repeatCount = 1;
enlargeAnimation.duration = 0.5;
enlargeAnimation.removedOnCompletion = NO;
enlargeAnimation.fillMode = kCAFillModeForwards;

//缩小图片的动画
CABasicAnimation* narrowAnimation = [[CABasicAnimation alloc] init];
narrowAnimation.keyPath = @"transform.scale";
narrowAnimation.beginTime = 0.9;
narrowAnimation.repeatCount = 1;
narrowAnimation.duration =0.3;
narrowAnimation.fromValue = [NSNumber numberWithFloat:1.8];
narrowAnimation.toValue = [NSNumber numberWithFloat:1];
//背景旋转
CABasicAnimation *bgImageViewTransformAnima = [CABasicAnimation animationWithKeyPath:@"transform.rotation.z"];
bgImageViewTransformAnima.beginTime = 0.5 ;

bgImageViewTransformAnima.duration = 1.5; // 持续时间
bgImageViewTransformAnima.repeatCount =5 ; // 重复次数
bgImageViewTransformAnima.fromValue = [NSNumber numberWithFloat:0.0]; // 起始角度
bgImageViewTransformAnima.toValue = [NSNumber numberWithFloat: M_PI]; // 终止角度

[self.bgImageView.layer addAnimation:bgImageViewTransformAnima forKey:@"rotate-layer"];

//1.创建组动画对象
CAAnimationGroup* animationGroup = [[CAAnimationGroup alloc] init];
animationGroup.animations = @[moveAnimation,enlargeAnimation,narrowAnimation];

// animationGroup.repeatCount = CGFLOAT_MAX;

animationGroup.repeatCount = 1;
animationGroup.duration = 1.2;
animationGroup.removedOnCompletion = NO;
animationGroup.fillMode = kCAFillModeForwards;

// 2.

CAAnimationGroup *animatonGroup2 = [[CAAnimationGroup alloc] init];
animatonGroup2.animations = @[bgImageViewTransformAnima];
animatonGroup2.duration = 1.5;
animatonGroup2.repeatCount = 4;
animatonGroup2.repeatCount = 1;
animatonGroup2.removedOnCompletion = NO;
animatonGroup2.fillMode = kCAFillModeForwards;
[self.bgImageView.layer addAnimation:animatonGroup2 forKey:@"ratate_layer.2"];
[self.gifImageView.layer addAnimation:animationGroup forKey:@"testAnimation"];    

}
‘

里面需要注意的

(1)我们可以给这个动画组设置在哪个时间点开始做什么东东 ,(根据beginTime 这个属性);
(2)做多久(根据.duration 这个属性)
(3)fillMode的作用就是决定当前对象过了非active时间段的行为. 比如动画开始之前,动画结束之后。如果是一个动画CAAnimation,则需要将其removedOnCompletion设置为NO,要不然fillMode不起作用.kCAFillModeRemoved 这个是默认值,也就是说当动画开始前和动画结束后,动画对layer都没有影响,动画结束后,layer会恢复到之前的状态
kCAFillModeForwards 当动画结束后,layer会一直保持着动画最后的状态
kCAFillModeBackwards 这个和kCAFillModeForwards是相对的,就是在动画开始前,你只要将动画加入了一个layer,layer便立即进入动画的初始状态并等待动画开始.你可以这样设定测试代码,将一个动画加入一个layer的时候延迟5秒执行.然后就会发现在动画没有开始的时候,只要动画被加入了layer,layer便处于动画初始状态
(4)

(5) 在组合动画中常用的animationWithKeyPath值的总结值

https://github.com/chenHuiMing5/WMCAAnimationGroup