最终效果
实现思路
动画的表现形式是颜色以及大小的变化，整体效果可以看做多个单独的波纹效果的叠加。因此我们可以创建多个CALayer，分别赋予CABasicAnimation动画，组成最终的动画效果。
因此我们先从单个波纹扩散效果来尝试，然后根据时间差将效果叠加起来。
代码
1.新建动画 View RippleAnimationView，动画效果在animationLayer上实现。
新建RippleAnimationView类，继承自UIView，设置扩散倍数，然后重写- (void)drawRect:(CGRect)rect方法，在方法内部新建承载动画的animationLayer。
#import
@interface RippleAnimationView : UIView
/**
设置扩散倍数。默认1.423倍
*/
@property (nonatomic, assign) CGFloat multiple;
- (instancetype)initWithFrame:(CGRect)frame;
@end
@implementation RippleAnimationView
- (instancetype)initWithFrame:(CGRect)frame {
self = [super initWithFrame:frame];
if (self) {
self.backgroundColor = [UIColor clearColor];
_multiple = 1.423;
}
return self;
}
- (void)drawRect:(CGRect)rect {
CALayer *animationLayer = [CALayer layer];
// 加入动画
[self.layer addSublayer:animationLayer];
}
2.创建单个扩散的动画承载CALayer，实现扩散效果。
首先实现缩放动画
- (CABasicAnimation *)scaleAnimation {
CABasicAnimation *scaleAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
scaleAnimation.fromValue = @1;
scaleAnimation.toValue = @(_multiple);
scaleAnimation.beginTime = CACurrentMediaTime();
scaleAnimation.duration = 3;
scaleAnimation.repeatCount = HUGE;// 重复次数设置为无限
return scaleAnimation;
}
新建CALayer，并在layer上加载动画。然后将这个Layer放在animationLayer上。
- (void)drawRect:(CGRect)rect {
CALayer *animationLayer = [CALayer layer];
// 新建缩放动画
CABasicAnimation *animation = [self scaleAnimation];
// 新建一个动画 Layer，将动画添加上去
CALayer *pulsingLayer = [self pulsingLayer:rect animation:animation];
//将动画 Layer 添加到 animationLayer
[animationLayer addSublayer:pulsingLayer];
[self.layer addSublayer:animationLayer];
}
- (CALayer *)pulsingLayer:(CGRect)rect animation:(CABasicAnimation *)animation {
CALayer *pulsingLayer = [CALayer layer];
pulsingLayer.borderWidth = 0.5;
pulsingLayer.borderColor = [UIColor blackColor].CGColor;
pulsingLayer.frame = CGRectMake(0, 0, rect.size.width, rect.size.height);
pulsingLayer.cornerRadius = rect.size.height / 2;
[pulsingLayer addAnimation:animation forKey:@"plulsing"];
return pulsingLayer;
}
可以看看现在的效果是这样的
3. 加入背景色以及边框色的渐变效果，将单一的缩放动画合并为动画组CAAnimationGroup。
（ps: 除了改变背景色，还要设置并改变边框色的更主要原因是去除锯齿）
// 设置一个初始化颜色的宏
#define ColorWithAlpha(r,g,b,a) [UIColor colorWithRed:r/255.0 green:g/255.0 blue:b/255.0 alpha:a]
- (void)drawRect:(CGRect)rect {
CALayer *animationLayer = [CALayer layer];
// 这里同时创建[缩放动画、背景色渐变、边框色渐变]三个简单动画
NSArray *animationArray = [self animationArray];
// 将三个动画合并为一个动画组
CAAnimationGroup *animationGroup = [self animationGroupAnimations:animationArray];
//修改方法，将原先添加的动画由“简单动画”改为“动画组”
CALayer *pulsingLayer = [self pulsingLayer:rect animation:animationGroup];
//将动画 Layer 添加到 animationLayer
[animationLayer addSublayer:pulsingLayer];
[self.layer addSublayer:animationLayer];
}
- (NSArray *)animationArray {
NSArray *animationArray = nil;
CABasicAnimation *scaleAnimation = [self scaleAnimation];
CAKeyframeAnimation *borderColorAnimation = [self borderColorAnimation];
CAKeyframeAnimation *backgroundColorAnimation = [self backgroundColorAnimation];
animationArray = @[scaleAnimation, backgroundColorAnimation, borderColorAnimation];
return animationArray;
}
- (CAAnimationGroup *)animationGroupAnimations:(NSArray *)array {
CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.beginTime = CACurrentMediaTime();
animationGroup.duration = 3;
animationGroup.repeatCount = HUGE;
animationGroup.animations = array;
animationGroup.removedOnCompletion = NO;
return animationGroup;
}
- (CABasicAnimation *)scaleAnimation {
CABasicAnimation *scaleAnimation = [CABasicAnimation animationWithKeyPath:@"transform.scale"];
scaleAnimation.fromValue = @1;
scaleAnimation.toValue = @(_multiple);
return scaleAnimation;
}
// 使用关键帧动画，使得颜色动画不要那么的线性变化
- (CAKeyframeAnimation *)backgroundColorAnimation {
CAKeyframeAnimation *backgroundColorAnimation = [CAKeyframeAnimation animation];
backgroundColorAnimation.keyPath = @"backgroundColor";
backgroundColorAnimation.values = @[(__bridge id)ColorWithAlpha(255, 216, 87, 0.5).CGColor,
(__bridge id)ColorWithAlpha(255, 231, 152, 0.5).CGColor,
(__bridge id)ColorWithAlpha(255, 241, 197, 0.5).CGColor,
(__bridge id)ColorWithAlpha(255, 241, 197, 0).CGColor];
backgroundColorAnimation.keyTimes = @[@0.3,@0.6,@0.9,@1];
return backgroundColorAnimation;
}
- (CAKeyframeAnimation *)borderColorAnimation {
CAKeyframeAnimation *borderColorAnimation = [CAKeyframeAnimation animation];
borderColorAnimation.keyPath = @"borderColor";
borderColorAnimation.values = @[(__bridge id)ColorWithAlpha(255, 216, 87, 0.5).CGColor,
(__bridge id)ColorWithAlpha(255, 231, 152, 0.5).CGColor,
(__bridge id)ColorWithAlpha(255, 241, 197, 0.5).CGColor,
(__bridge id)ColorWithAlpha(255, 241, 197, 0).CGColor];
borderColorAnimation.keyTimes = @[@0.3,@0.6,@0.9,@1];
return borderColorAnimation;
}
- (CALayer *)pulsingLayer:(CGRect)rect animation:(CAAnimationGroup *)animationGroup {
CALayer *pulsingLayer = [CALayer layer];
pulsingLayer.borderWidth = 0.5;
pulsingLayer.borderColor = ColorWithAlpha(255, 216, 87, 0.5).CGColor;
pulsingLayer.frame = CGRectMake(0, 0, rect.size.width, rect.size.height);
pulsingLayer.cornerRadius = rect.size.height / 2;
[pulsingLayer addAnimation:animationGroup forKey:@"plulsing"];
return pulsingLayer;
}
现在就有种渐变的感觉了
4. 同时创建三个扩散动画的CALyer，将开始动画的时间错开，同时添加到animationLayer上。
// 设置静态常量 pulsingCount ，表示 Layer 的数量
static NSInteger const pulsingCount = 3;
// 设置静态常量 animationDuration ，表示动画时间
static double const animationDuration = 3;
- (void)drawRect:(CGRect)rect {
CALayer *animationLayer = [CALayer layer];
// 利用 for 循环创建三个动画 Layer
for (int i = 0; i < pulsingCount; i++) {
NSArray *animationArray = [self animationArray];
// 通过传入参数 i 计算，错开动画时间
CAAnimationGroup *animationGroup = [self animationGroupAnimations:animationArray index:i];
CALayer *pulsingLayer = [self pulsingLayer:rect animation:animationGroup];
[animationLayer addSublayer:pulsingLayer];
}
[self.layer addSublayer:animationLayer];
}
... ...
- (CAAnimationGroup *)animationGroupAnimations:(NSArray *)array index:(int)index {
CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.beginTime = CACurrentMediaTime() + (double)(index * animationDuration) / (double)pulsingCount;
animationGroup.duration = animationDuration;
animationGroup.repeatCount = HUGE;
animationGroup.animations = array;
animationGroup.removedOnCompletion = NO;
return animationGroup;
}
... ...
然后效果有点……一言难尽……
真是很有纪律性的变化啊~~好吧，只需要加入动画曲线就好了
5. 最后加入动画速度曲线
... ...
- (CAAnimationGroup *)animationGroupAnimations:(NSArray *)array index:(int)index {
CAAnimationGroup *animationGroup = [CAAnimationGroup animation];
animationGroup.beginTime = CACurrentMediaTime() + (double)(index * animationDuration) / (double)pulsingCount;
animationGroup.duration = animationDuration;
animationGroup.repeatCount = HUGE;
animationGroup.animations = array;
animationGroup.removedOnCompletion = NO;
// 添加动画曲线。关于其他的动画曲线，也可以自行尝试
animationGroup.timingFunction = [CAMediaTimingFunction functionWithName:kCAMediaTimingFunctionDefault];
return animationGroup;
}
... ...
如果需要点扩散，那就设置 frame 极小，同时扩散倍数增大即可。
将动画View垫在另一个圆形View之下即可实现最上方的效果。关闭背景色，重调边框色和边框宽度即可实现第二种效果。