How to implement a custom keyboard pop on an iPhone

I have a tabviewcontroller and within that is a navigationcontroller and tableview. When i tap on one of the tab开发者_如何学JAVAle rows I want a custom keyboard to pop up. (This will be some simple plus and minus buttons to increase/decrease a counter on the tablerow item)

I'm assuming I create a View Controller and add it as a subview but how do I add it so that it pops over the tab bar?

What would be the general steps to do this?

Custom Views for Data Input