Re: NSObject vs id

On Sep 3, 2009, at 10:14 AM, Christiaan Hofman wrote:

> The basic rule is that you can assume that all objects (type id)  
> should at least respond to the basic memory management methods and - 
> description (basically the Cocoa counterparts of CFBase.h).

For practical purposes only, you can assume that.

If I implement:

@interface Rootonomous
@end

Instances of said class will not implement any methods.  Though rare  
and typically limited purely to research purposes, there are reasons  
to implement such a class (actually, it is an interesting thought  
exercise to take the above and design your own object library w/your  
own patterns of use).

Such classes cannot be used in the context of the Foundation [unless  
you were to implement <NSObject>, which kind of defeats the purpose of  
the exercise), though, certainly and, thus, Christiaan's statement is  
true in the context of Cocoa programming, for all intents and purposes.

> For other methods you should first know they responds, usually using  
> respondsToSelector: (or you know it from a context, e.g. when the  
> object is a delegate or dataSource with required methods).

Using respondsToSelector: outside of delegation or protocols with  
optional methods is generally a sign that your design has gone in an  
unfortunate direction.

b.bum