My app allows users to format text in a UITextView by using some custom formatting buttons I've created. Now I want to enable the allowsEditingTextAttributes property of the text view so that users can copy and paste formatted text between text views. This enables the bold/italic/underline buttons in the standard UIMenuController for the text view. This is fine, but when users change the formatting through this menu, I need to call my custom method that updates the state of my custom formatting buttons. How can I detect that a user has tapped one of the UIMenuController's formatting buttons?
I looked for notifications in the UITextView and UIMenuController class references, but didn't see anything relevant. These formatting buttons don't trigger a UITextViewTextDidChangeNotification and don't trigger the textViewDidChange: method of the UITextViewDelegate. I also tried subclassing the UITextView class to override a method there, but I don't know what method to override. It looks like a bold: method doesn't exist, for example, even though a paste: method does exist there. Does anyone know what method of what class is called when tapping one of the bold/italic/underline buttons?
These buttons aren't mentioned in the Text Programming Guide for iOS or the UIMenuController class reference, as far as I can tell.