自定义按钮动画

自定义一个类，继承与UIButton。

-(void)sendAction:(SEL)action to:(id)target forEvent:(UIEvent *)event{

    [super sendAction:action to:target forEvent:event];
    
    //按钮点击时的效果
    CAShapeLayer * layer = [[CAShapeLayer alloc]init];
    layer.frame = self.bounds;
    layer.strokeColor = [UIColor clearColor].CGColor;
    layer.fillColor = [[UIColor blackColor] colorWithAlphaComponent:0.1].CGColor;
    [self.layer addSublayer:layer];
    

    UIBezierPath * pathStart = [UIBezierPath bezierPath];
    pathStart = [UIBezierPath bezierPathWithOvalInRect:self.bounds]; //椭圆形，如果是rect是正方形，则是圆形。
    
    UIBezierPath * pathEnd = [UIBezierPath bezierPathWithOvalInRect:CGRectInset(self.bounds, -5, -5)];
    

    CABasicAnimation *animation = [CABasicAnimation animationWithKeyPath:@"path"];
    animation.delegate = self;
    animation.fromValue = (__bridge id)pathStart.CGPath;
    animation.toValue =  (__bridge id)pathEnd.CGPath;
    animation.duration = 0.25f;
    animation.timingFunction = [CAMediaTimingFunction  functionWithName:kCAMediaTimingFunctionEaseInEaseOut];
    [layer addAnimation:animation forKey:@"path"];
    
  
    
}