Important:
This text input management system described in this document is deprecated as of Mac OS X v10.6. Please see Input Method Kit Framework Reference, which describes the replacement technology for creating input methods, NSTextInputClient Protocol Reference, which describes the replacement technology for NSTextInput protocol, and NSTextInputContext Class Reference, which describes the replacement technology for NSInputManager class.
Input managers use a dictionary property list, called a key-bindings dictionary, to interpret keyboard events before passing them to an input server.
During the processing of a keyboard event, the event passes
through the NSMenu object, then to
the first responder via the keyDown: method.
The default implementation of the method provided by the NSResponder
class propagates
the message up the responder chain until an overridden keyDown: implementation
stops the propagation. Typically, an NSResponder subclass can choose
to process certain keys and ignore others (for example, in a game)
or to call the interpretKeyEvents: method,
which passes the event to the current input manager.
The input manager checks the event
to see if it matches any of the keystrokes in the user’s key-bindings
dictionary. A key-bindings dictionary maps a keystroke (including
its modifier keys) to a method name. For example, the default key-bindings
dictionary maps ^d (Control-D)
to the method name deleteForward:.
If the keyboard event is in the dictionary, then the input manager
calls the input server’s doCommandBySelector:client: method
with the selector associated with the dictionary entry. If the input
server’s doCommandBySelector:client: method
doesn’t find a matching method, then it passes the command selector onto the text view’s doCommandBySelector: method,
which may or may not find a matching method to call.
If the input manager cannot match the keyboard event to an
entry in the key-bindings dictionary, it extracts the string from
the event by using its characters method
and passes the returned characters to the input server’s insertText:client: method.
The standard key-bindings dictionary is in the file /System/Library/Frameworks/AppKit.framework/Resources/StandardKeyBinding.dict.
You can override the standard dictionary entirely by providing a
dictionary file at the path ~/Library/KeyBindings/DefaultKeyBinding.dict. However, defining custom key bindings dynamically (that is, while the application is running) is not supported.
Last updated: 2009-06-02
