之前做了一个仿苹果地图定位时的Annotation扩散动画
需求是做一组扩散动画在地图上表示紧急求助状态
网上也没有对应此类需求的动画效果 所以记录一下 希望可以帮助到需要的人
基于CAAnimationGroup 来做的一组动画 （动画参数调试比较费时）

紧急扩散动画.gif

代码

直接上代码吧 关于CAAnimation 的一些参数和API的使用在这里就不详细说了 网上一大堆 想研究的可以看看AE公司的开源项目Lottie的源码 CA动画绘制矢量动画的典例 很牛逼
后面会把一些关于地图的小东西和多地图框架做一个demo上传GitHub 供大家探讨

.h

/**
 一个呼吸动画的layer
 */

+ (CAAnimationGroup *)pulseAnimationGroup;

/**
 一个圆形色彩扩散动效的layer

 @param size layer size
 @param time annimation offset time
 @return annimation layer
 */
+ (CALayer*)colorDotLayerWithSize:(CGSize)size WithBeginTime:(NSTimeInterval)time;


/**
 一组扩散动效 layer 三个layer
 */
+ (CALayer *)groupLayerAnimationsWithSize:(CGSize )size;

.m

+ (CAAnimationGroup *)pulseAnimationGroup
{
    CAAnimationGroup *pulseAnimationGroup = [CAAnimationGroup animation];
    
    CAMediaTimingFunction *defaultCurve = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
    
    pulseAnimationGroup = [CAAnimationGroup animation];
    pulseAnimationGroup.duration = 2;
    pulseAnimationGroup.repeatCount = INFINITY;
    pulseAnimationGroup.removedOnCompletion = NO;
    pulseAnimationGroup.timingFunction = defaultCurve;
    
    NSMutableArray *animations = [NSMutableArray new];
    
    CABasicAnimation *pulseAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale.xy"];
    pulseAnimation.fromValue = @0.0;
    pulseAnimation.toValue = @1.0;
    pulseAnimation.duration = 3;
    [animations addObject:pulseAnimation];
    
    CAKeyframeAnimation *animation = [CAKeyframeAnimation animationWithKeyPath:@"opacity"];
    animation.duration = 3;
    animation.values = @[@0.45, @0.45, @0];
    animation.keyTimes = @[@0, @0.2, @1];
    animation.removedOnCompletion = NO;
    [animations addObject:animation];
    
    pulseAnimationGroup.animations = animations;
    
    return pulseAnimationGroup;
}

+ (CALayer*)colorDotLayerWithSize:(CGSize)size WithBeginTime:(NSTimeInterval)time {
       CALayer *colorDotLayer = [CALayer layer];
        CGFloat width = size.width - 6;
        colorDotLayer.bounds = CGRectMake(0, 0, width, width);
        colorDotLayer.allowsGroupOpacity = YES;
        colorDotLayer.backgroundColor = [UIColor colorWithRed:243 / 255.0
                                                        green:53 / 255.0
                                                         blue:43 / 255.0 alpha:1].CGColor;
        colorDotLayer.cornerRadius = width/2;
        colorDotLayer.position = CGPointMake(size.width/2, size.height/2);
        
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0), ^(void) {
            
            CAMediaTimingFunction *defaultCurve = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
            
            CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
            animationGroup.duration = 3;
            animationGroup.repeatCount = INFINITY;
            animationGroup.removedOnCompletion = NO;
//            animationGroup.autoreverses = YES;
            animationGroup.timingFunction = defaultCurve;
//            animationGroup.speed = 1;
            animationGroup.fillMode = kCAFillModeBoth;
            animationGroup.timeOffset = time;
            
            CABasicAnimation *pulseAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale.xy"];
            pulseAnimation.fromValue = @0.25;
            pulseAnimation.toValue = @1;
            pulseAnimation.duration =3;
            
            CABasicAnimation *opacityAnimation = [CABasicAnimation animationWithKeyPath:@"opacity"];
            opacityAnimation.fromValue = @1;
            opacityAnimation.toValue = @0.;
            opacityAnimation.duration = 3;
            
            animationGroup.animations = @[pulseAnimation, opacityAnimation];
            
            dispatch_async(dispatch_get_main_queue(), ^(void) {
                [colorDotLayer addAnimation:animationGroup forKey:@"pulse"];
            });
        });
    return colorDotLayer;
}

+ (CALayer *)groupLayerAnimationsWithSize:(CGSize )size
{
    CALayer *groupLayer = [CALayer layer];
    CGFloat width = size.width;
    groupLayer.bounds = CGRectMake(0, 0, width, width);
    groupLayer.allowsGroupOpacity = YES;
    groupLayer.cornerRadius = width/2;
    groupLayer.position = CGPointMake(size.width/2, size.height/2);
    CALayer *oneLayer = [self colorDotLayerWithSize:size WithBeginTime:0];
    CALayer *twoLayer = [self colorDotLayerWithSize:size WithBeginTime:1.];
    CALayer *threeLayer = [self colorDotLayerWithSize:size WithBeginTime:2];
    
    [groupLayer addSublayer:oneLayer];
    [groupLayer addSublayer:twoLayer];
    [groupLayer addSublayer:threeLayer];
    return groupLayer;
}