UIPeripheralHostView contains the iOS keyboard. It is made up of the background (UIKBInputBackdropView) and the foreground (UIKeyboardAutomatic).
The keyboard button squares and the text are actually separate images. Each are contained in a UIKBSplitImageView which has a UIImage. These are rendered and cached.
The more dynamic keys (shift, delete, space, 123, world icon, return, etc) are UIKBKeyViews.
The best way to get the UIPeripheralHostView is via [%c(UIPeripheralHost) activeInstance]'s _hostView ivar.