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My program sometimes crashes when the following code is called and I can’t figure out why. I get a sigbus error from NSIntersectionRange(). When I break on my method and try to step through it everything is fine, the program doesn’t crash. Can someone with a better understanding of pointers help me figure this out?

The code below is supposed to remove the NSLinkTextAttribute from an NSAttributedString in my textView.

Both the original post and the reply above belie a horrible misunderstanding of the situation. (No offense, it’s just the kind of thing that will make horrible, hard-to-find bugs.)

The attribute:… method asks for an NSRangePointer because it’s returning an NSRange. Thus, you should not be passing it a variable NSRangePointer, initialized to nil or otherwise. What you should be doing is passing it a pointer to an existing NSRange, like this:

NSRange annotationRange; id attribute = textView textStorage] attribute:[[NSLinkAttributeName atIndex:[textView selectedRange].location effectiveRange:&annotationRange];

The range will be returned to the range variable.

When something asks for a pointer, you must always give it a pointer that is either nil or points to something interesting. If the pointer is used to return information, it must point to some space for that information.

To whom:

Thanks for the info. That worked perfectly. I have been able to get along with very little knowledge of C so far but this one bit me. I edited your post for clarity. Thanks for correcting my laziness, it’s much easier to read now.

Pointers are the most important thing you could possibly know about C. If you don’t know about them, that will be the cause of about 70% of your problems.