NSRangeException - why?

Question

This seems like a basic question.. but my array size is 64 and I am replacing an object at index 63. Like this:

[myMutableArray replaceObjectAtIndex:myIndex withObject:myObj];

So I have no idea why gdb is telling me this:

*** Terminating app due to uncaught exception 'NSRangeException', reason: '*** -[NSCFArray objectAtIndex:]: index (64) beyond bounds (64)'

Why is it saying my index is 64? I'm passing in 63.

Thanks.

Answer 1

Try NSLog'ing the value of myIndex just before the call, or looking for other places that could be causing this exception.

Try breaking on -[NSException raise] and/or objc_exception_throw to see where it's coming from. (See here about exception breakpoints.)