Disabling ESC and Command . in an OSX Cocoa app

Question

I made a little cocoa app that brings up an IKPictureTaker and saves a picture to a file if you press the set button. Currently, if you press esc or Command . the window picture taker will close. Is there a way to disable this behavior?

Answer 1

You need to insert yourself somewhere in the responder chain in time to catch the escape key down event, and disable it. You may have to subclass IKPictureTaker . The snippet below should help you ( source ).

- (void)keyDown:(NSEvent *)event {
   if ([event keyCode] == 53) {
        NSLog(@"Escape has been pressed");
   }
}

Answer 2

Another approach is to hide the close and Cancel buttons, so they can't be pressed:

IKPictureTaker *taker = [IKPictureTaker pictureTaker];
[taker setStyleMask:0]; //disable close button
for(NSView *aView in [[taker contentView] subviews]){
 if([aView isKindOfClass:[NSButton class]]){
  NSButton *aButton = (NSButton*)aView;
  if([aButton action] ==  @selector(cancelButton:))
   [aButton setHidden:YES];
 }
}

Answer 3

If you want/need to drop down to the low level, see the CGEvent API. Using it, you'd create a tap and swallow/modify specific events.