查看动画不适用于shadowRadius iOS

我想要做的是模拟我的按钮周围的脉冲.我可以使用发光效果来改变按钮图层的属性.但是,我无法让它变得生动.
这是我到目前为止所尝试的：

UIColor *confirmButtonColor = self.btnConfirm.currentTitleColor;
self.btnConfirm.layer.shadowOffset = CGSizeZero;

self.btnConfirm.layer.masksToBounds = NO;
self.btnConfirm.layer.shadowColor = confirmButtonColor.CGColor;
self.btnConfirm.layer.shadowRadius = 6.0f;
 self.btnConfirm.layer.shadowOpacity = .0f;
[UIView animateWithDuration:1.2 delay:5 options:UIViewAnimationCurveLinear animations:^{
    self.btnConfirm.layer.shadowOpacity = 1.0f;
}completion:nil];

发光没有动画;
我还尝试将所有代码放在动画中并且没有改变.
是的,我导入Quartz.

谢谢

我不清楚你为什么没有工作(也许有人可以启发我们),但这有效：

UIColor *confirmButtonColor = self.btnConfirm.currentTitleColor;
self.btnConfirm.layer.shadowOffset = CGSizeZero;

self.btnConfirm.layer.masksToBounds = NO;
self.btnConfirm.layer.shadowColor = confirmButtonColor.CGColor;
self.btnConfirm.layer.shadowRadius = 6.0f;
self.btnConfirm.layer.shadowOpacity = 1.0f; // Note: You need the final value here
CABasicAnimation* animation = [CABasicAnimation animationWithKeyPath:@"shadowOpacity"];
animation.fromValue = [NSNumber numberWithFloat:.0];
animation.toValue = [NSNumber numberWithFloat:1.0];
[self.btnConfirm.layer addAnimation:animation forKey:@"shadowOpacity"];