Handling keyboard events on cocoa

I have a textbox and every time something is typed into it. I want to captur开发者_开发知识库e the key pressed and perform some action. For this I need to capture the keyboard event. Currently I am trying to override the keyDown: function but it wont work.

So how can I do it?

Don't override keyDown. Register for notifications when the text control text has changed. The following will work for an NSTextField:

// Listen for change events on fields
[[NSNotificationCenter defaultCenter] addObserver:self
                                         selector:@selector(valueChanged:)
                                             name:@"NSControlTextDidChangeNotication"
                                           object:textField ];

...

 (void) valueChanged:(NSNotification*)notification {
  // TODO  -- look at the stringValue of your TextField
}

You can use

- (void)controlTextDidChange:(NSNotification *)aNotification

This will be use full if you need to validate the data in your textField ....