How Do Classes Respond to performSelector?

FROM : Francisco Tolmasky
DATE : Wed Jan 30 22:14:45 2008

This is just a question out of curiosity.  In the developer docs, only 
- (id)performSelector: is defined.
So I was going to write my own + (id)perfromSelector, but first 
figured I'd check whether there was
one already by writing up a quick test in XCode - which it turns out 
there is (saved me the work).
I figured it must just not be in the documentation, so I was going to 
file a bug on the developer docs...
Yet, doing a classdump on Foundation.framework doesn't show + 
performSelector either (only on
NSProxy, not on NSObject).  Is there some magic going on?  Is 
+performSelector actually not defined
on NSObject and this is getting forwarded to NSProxy or something?  Or 
is this just a case of under
documentation and class dump not telling the whole truth?

Thanks,

Francisco