UIPeripheralHostView contains the iOS keyboard. It is made up of the background (UIKBInputBackdropView) and the foreground (UIKeyboardAutomatic).
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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.