This concept seems to trouble me. Why does an NSError object need its pointer passed to a method that is modifying the object? For instance, wouldn't just passing a reference to the error do the same thing?

NSError *anError;
[myObjc doStuff:withAnotherObj error:error];

and then in doStuff:

 - (void)doStuff:(id)withAnotherObjc error:(NSError *)error 
 {
    // something went bad!
    [error doSomethingToTheObject];
 }

Why doesn't the above work like most other object messaging patterns work? Why must instead we use error:(NSError **)error?

c objective-c cocoa pointers
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