Customize numeric keyboard in iPhone

I need to add cancel button in numeric keyboard. How to customize the following keyboard? When I click 开发者_运维问答by cancel button, the keyboard will be hide.

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Input Accessory View is a view that sits on top of the keyboard. It has to the be the width of the keyboard and the height is adjustable.

On this view you could add a button, that when pressed will ResignFirstResponder of the UITextField, thus giving you the funcationality you want.