Match look and feel of default keyboard with a custom keyboard on the iPad

Question

I have an iPad app that needs a custom number keyboard on a view that also has a text field using the default keyboard. I have attempted to match the look of the default keyboard by drawing a gradient on a layer of the input view and using custom images on the UIButtons.

Is there a better way to create a custom keyboard that matches the look and feel of the default keyboard?

Thanks, alex