Using the Window’s Field Editor
Each window has a text object that is shared for light editing tasks. This object, the window’s field editor, is inserted in the view hierarchy when an object needs to edit some text and removed when the object is finished. The field editor is used by
NSTextField objects and other controls, for example, to edit the text that they display. The
fieldEditor:forObject: method returns a window’s field editor, after asking the delegate for a substitute using
windowWillReturnFieldEditor:toObject:. You can override the
fieldEditor:forObject: method of
NSWindow in subclasses or provide a delegate to substitute a class of text object different from the
NSTextView default, thereby customizing text editing in your application.