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Editorial Team
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Asked: 2026-05-23T12:02:50+00:00

Why can’t I do NSLog(@mySet count: %@, [mySet count]); and use the NSSet afterwards?

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Why can’t I do

NSLog(@"mySet count: %@", [mySet count]);

and use the NSSet afterwards? (if I do use it the app crashes with “EXC_BAD_ACCESS”

I’ve tried mutable/immutable, retained, copied, autoreleased… all kinds of sets, And after the count message they all become useless and crash. And if I don’t count they behave as expected, And if I print them out like this:

NSLog(@"mySet: %@", mySet);

it’s fine! the problem seems to be just with count.

can someone explain me this? I’ve searched and found nothing regarding this strange behaviour

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1 Answer

  1. Editorial Team

    The reason this crashes is because [mySet count] returns an integer, and the %@ format specifier expects an object. Change it to:

    NSLog(@"mySet count: %lu", [mySet count]);

    This is one of the “gotchas” of Objective C (unless you are already familiar with C or C++): sometimes your data is an object and sometimes your data is not an object. This is necessary for compatibility with C code.

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