UIViewPropertyAnimator重复不起作用

Question

我正在使用UIViewPropertyAnimator为淡入和淡出设置动画。传递重复选项不会重复播放动画，只能工作一秒钟。

我做错什么了吗？

有问题的代码：

private func faceFadeAnimator() {
            faceAnimator = UIViewPropertyAnimator.runningPropertyAnimator(withDuration: 1, delay: 0, options: [.curveLinear, .repeat], animations: {
                self.animatorImageView.alpha = self.animatorImageView.alpha == 1 ? 0 : 1
            }, completion: { (position) in
            })
        }

解决方法：

private func faceFadeAnimator() {
        faceAnimator = UIViewPropertyAnimator.runningPropertyAnimator(withDuration: 1, delay: 0, options: [.curveLinear], animations: {
            UIView.setAnimationRepeatCount(1000)
            self.animatorImageView.alpha = self.animatorImageView.alpha == 1 ? 0 : 1
        }, completion: { (position) in
        })
    }