How they heck did they do this? Custom number pad

http://itunes.apple.com/us/app/bistromath/id309214622?mt=8

Number pad in second screenshot:

So is this some c开发者_开发问答ustomization of the stock keypad? Modal view?

Customizing the keyboard is still completely unsupported, so it must be a custom view.

Yes, it's a customized view including UIButtons