iOS Programming: The Big Nerd Ranch Guide

For the More Curious: UIMenuController and UIResponderStandardEditActions

The UIMenuController is typically responsible for showing the user an “edit” menu when it is displayed. (Think of a text field or text view when you press and hold.) Therefore, an unmodified menu controller (one that you do not set the menu items for) already has default menu items that it presents, like Cut, Copy, and other familiar options. Each item has an action message wired up. For example, cut: is sent to the view presenting the menu controller when the Cut menu item is tapped.

All instances of UIResponder implement these methods, but, by default, these methods do not do anything. Subclasses like UITextField override these methods to do something appropriate ...