transitionWithView翻转UIView时，如何取消view的颜色变暗问题？

Question

想做一个类似卡牌正反面翻转的动画，使用UIView 的transitionWithView方法，会导致所翻转的view颜色变暗，如果view的背景色是白色的化，翻转时就会有个闪烁、黑色中线的问题，效果很不好，求各路大神指教···

[UIView transitionWithView:cardView duration:0.8f options:UIViewAnimationOptionTransitionFlipFromLeft animations:^{
        [cardView exchangeSubviewAtIndex:0 withSubviewAtIndex:1];
    } completion:NULL];

Answer 1

    [UIView transitionFromView:self.aView toView:self.bView duration:0.5 options:UIViewAnimationOptionTransitionFlipFromLeft completion:^(BOOL finished) {
        // do something such as hidden or remove
    }];