UITableViewCell popular animation (flipping around Y axis, depending on scroll direction)

gistfile1.m

@interface YourViewController : UIViewController <UITableViewDelegate, UITableViewDataSource> {
    UIImageOrientation scrollOrientation;
    CGPoint lastPos;
}

- (void) tableView:(UITableView *)tableView willDisplayCell:(UITableViewCell *)cell forRowAtIndexPath:(NSIndexPath *)indexPath {
    if (tableView.isDragging) {
        UIView *myView = cell.contentView;
        CALayer *layer = myView.layer;
        CATransform3D rotationAndPerspectiveTransform = CATransform3DIdentity;
        rotationAndPerspectiveTransform.m34 = 1.0 / -1000;
        if (scrollOrientation == UIImageOrientationDown) {
            rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, M_PI*0.5, 1.0f, 0.0f, 0.0f);
        } else {
            rotationAndPerspectiveTransform = CATransform3DRotate(rotationAndPerspectiveTransform, -M_PI*0.5, 1.0f, 0.0f, 0.0f);
        }
        layer.transform = rotationAndPerspectiveTransform;
        [UIView animateWithDuration:.5 animations:^{
            layer.transform = CATransform3DIdentity;
        }];
    }
}

- (void) scrollViewDidScroll:(UIScrollView *)scrollView {
    scrollOrientation = scrollView.contentOffset.y > lastPos.y?UIImageOrientationDown:UIImageOrientationUp;
    lastPos = scrollView.contentOffset;
}

Do you know why the cell view overlaps the another one if let cell.layer.anchorPoint = CGPointMake(0.5, 0) when scrolling?