覆盖keyDown：在NSTableView类别中禁用箭头键处理

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?

Answer 1

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?