Re: Using NSSortDescriptor to reverse sort an NSArray containing NSString objects

FROM : Ken Thomases
DATE : Fri Jun 06 23:51:45 2008

On Jun 6, 2008, at 4:16 PM, Adam R. Maxwell wrote:

> On Friday, June 06, 2008, at 02:07PM, "George Stuart" <george.<email_removed>
> > wrote:
>

>> The suggestion of using a keyPath of @"self" presents another 
>> question:
>> 1)  I assume NSSortDescriptor is using valueForKeyPath:, which in
>> turns calls valueForKey: some number of times, to get the object for
>> the keyPath I specified.  Is it defined behavior that sending an
>> object valueForKey:@"self" will return the object itself?

>
> I always use self as the key path in cases like this, since -
> [NSObject self] is documented to return the receiver.


And, to complete the picture, the documentation for valueForKey: 
describes how that method obtains the value for the key.  The first 
step in its search for key @"self" would be to look for the method 
named "self".


>  It has the advantage of working with objects other than strings.


Well, so does -description. ;)  It just gives a different thing.  That 
is, -self always returns the receiver, while -description only returns 
the receiver for an NSString, but always returns something (a string) 
that may be useful for a given purpose (possibly even sorting).

Cheers,
Ken