How to change the background color of the keyboard programmatically in iPhone sdk?

I want to change the background color of开发者_如何学编程 the keyboard when we are entering text in a textfield or textview. The default color is blue for the background. How can I change this to black?

You can get a dark gray background if you set the Appearance of the Text Input Traits of the Text Field to Alert. You can do this in Interface Builder under the Text Field attributes in the inspector.

Unfortunately Apple only opens two Appearance styles for the keyboard to us 3rd party developers.