Re: Subclassing NSArray
Re: Subclassing NSArray
- Subject: Re: Subclassing NSArray
- From: email@hidden
- Date: Sun, 15 Sep 2002 09:18:04 -0400
You only need to implement the principal methods.
See the "Class Clusters" programming topic at <URL:
file:///Developer/Documentation/Cocoa/TasksAndConcepts/
ProgrammingTopics/Foundation/
Concepts/ClassClusters.html> for more.
On Sunday, Sep 15, 2002, at 09:00 America/New_York, Timothy Larkin
wrote:
I am having difficulty subclassing NSArray. The subclass does not
inherit NSArray's methods. For instance, if MyThing is a subclass of
NSArray, and A is an instance of MyThing, then [A count] produces an
execution error that says:
2002-09-15 08:54:39.158 ArrayTest[14121] *** Uncaught exception:
<NSInvalidArgumentException> *** -count only defined for abstract
class. Define -[MyThing count]!
From this I gather that 'count' is defined only for the NSArray
abstract class, and that a subclass of NSArray is expected to be a
concrete class that explicity implements 'count'. However, I don't
want to create an entire concrete class; I just want to subclass and
add a few methods.
Is subclassing NSArray impossible? Do I need to use categories
instead?
--
Timothy Larkin
Abstract Tools
Caroline, NY
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