图标抖动

  //创建一个帧动画
  CAKeyframeAnimation *anim = [CAKeyframeAnimation animation];
  //设置属性
  anim.keyPath = @"transform.rotation";
 //设置属性值
 anim.values = @[@(angle2Rad(-5)) ,@(angle2Rad(5)),@(angle2Rad(-5))];
 anim.repeatCount = MAXFLOAT;
 anim.duration = 0.25;
 [self.imageView.layer addAnimation:anim forKey:nil];