自定义iPad键盘，看起来像系统键盘

I'm looking for a non-hackish solution for this, so basically -inputView. The part that I'm not sure about is how to make it look like the regular keyboards, from the background to the keys. I realize that I could photoshop an apple keyboard, but this seems like it is a little hackish, especially if apple (probably not but still possible) decides to change the look of their keyboards. I know Numbers has done an excellent job of making extra keyboards that look like the standard system ones, and I would like to do it like those (although obviously they have access to the same resources that made the system keyboards, including possible private frameworks, etc.) I'm looking for a non-hackish solution for this