If you want to make an animation similar to flipping the front and back of a card, using the transitionWithView method of UIView will cause the color of the flipped view to darken. If the background color of the view is white, there will be flickering and black when flipping. Regarding the problem of the center line, the effect is very poor. Please give me some advice from all the experts...

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