如果直接指定cell.backgroundColor = = [UIColor colorWithRed:255.0/255.0 green:255.0/255.0 blue:255.0/255.0 alpha:0.8];在ios7下改变cell高度时cell背景会闪

通过以下方法可避免此问题，将cell对背景色clear，cell的contentView的背景色置为半透明

cell.backgroundColor = [UIColor clearColor];

cell.contentView.backgroundColor = [UIColor colorWithRed:255.0/255.0 green:255.0/255.0 blue:255.0/255.0 alpha:0.8];