Overriding keyDown: in an NSTableView category disables arrow key handling

Question

I have an NSTableView and I have some issues with its default behavior.

If I've overridden the keyDown: method in a category as follows:

- (void) keyDown:(NSEvent *)event {
    [super keyDown:event];
}

I can't change the row selection with the keyboard arrow keys anymore. Why is that?

No, in a category of NSTableView. I haven't written the category, but the - (void) keyDown:(NSEvent *)event method is overridden there. — aneuryzm, Dec 19 '11 at 15:43

score 7 · Accepted Answer · edited May 23 '17 at 12:10

in a category of NSTableView.

In a category of NSTableView, super refers to NSTableView's superclass (NSControl), not to NSTableView as it would in a subclass. You're passing the event on to the NSControl version of keyDown:, which knows nothing about table views and can't handle the arrow keys the way you want.

If you override a method in a category, there's no way to call the original method. It's almost never a good idea to do this on framework classes (whose source is unavailable to you). Use a subclass.

Cf. Using Super in an Objective C Category? and Is calling super in a category the same as calling it in a subclass?

Overriding keyDown: in an NSTableView category disables arrow key handling

1 Answers1