点击cell时subView背景色消失

在自定义cell中使用如下方法：

- (void)setHighlighted:(BOOL)highlighted animated:(BOOL)animated
{
    UIColor *backgroundColor = self.subView.backgroundColor;
    [super setHighlighted:highlighted animated:animated];
    self.subView.backgroundColor = backgroundColor;
}

- (void)setSelected:(BOOL)selected animated:(BOOL)animated
{
    UIColor *backgroundColor = self.subView.backgroundColor;
    [super setSelected:selected animated:animated];
    self.subView.backgroundColor = backgroundColor;
}