Adding categories: first try.

[fiz]

Hello,

I’m trying to add new categories to the NSArrayController class: it can select the first and the last item. I did so:

#import “NSArrayController+selectEnds.h”

@implementation NSArrayController (selectEnds)

• (void)selectFirst:(id)sender {
  if (self.arrangedObjects !=nil){ BOOL ignore = [self setSelectionIndex:0];}
  }
• (void)selectLast:(id)sender {
  if (self.arrangedObjects !=nil){
  NSUInteger lastItem = [self.arrangedObjects count]-1;
  BOOL ignore = [self setSelectionIndex];}
  }
  @end

I get no errors, but I would like to but this object in IB, using a blue cube and binding buttons to its “selectFirst” and “selectLast” methods.

But I’m a bit lost: which standard object to start with? A standard ArrayController? And then, which class name to choose to have the new methods listed?

Thanks for your help.

[Shane_Stanley]

For categories you don’t have to do anything differently in IB.

[fiz]

That’s right. Having

#import <Cocoa/Cocoa.h>
@interface NSArrayController (selectEnds)

• (IBAction)selectFirst:(id)sender;
• (IBAction)selectLast:(id)sender;
  @end

The new methods appear in the binding window of the standard NSArrayController. Incredible. Once again it’s like magic. 10 more lines of IF-ed code gone – and it works.

Thanks!

[Shane_Stanley]

You could probably use:

#import "NSArrayController+selectEnds.h"

instead.

[fiz]

Yes, of course, it was unclear from my post but I have a .h and a .m file.

Categories are really fun. As long as I don’t add instance variables/properties, I can obtain from a existing class just this “why didn’t they implement this method” extra work – and certainly reusable.

Thank you, Shane, your MyriadHelpers have inspired me!

Of course if I wanted something more complicated, like, for example, a NSSegmentedControl made of individual buttons instead of segments, able to send n different actions, subclassing would be unavoidable.

What I miss for the moment is a custom cell capable of implementing a NSColorWell into a standard cell-based table view. Still searching to subclass NSControlCell and filling the log console with pages of errors.

Regards,

[StefanK]

@fiz

What I miss for the moment is a custom cell capable of implementing a NSColorWell into a standard cell-based table view. Still searching to subclass NSControlCell and filling the log console with pages of errors.

A table view cell can also be a custom NSCell which can contain custom UI elements.
For an example have a look at http://ringce.com/code/Cocoa/lvcolorwellcell

[fiz]

Thank you, Stefan, Volltreffer.

That’s the kind of thing I was looking for.