Strange bug in NSMutableArray removeObject

Question

I have this snippet:

1: if ((s >= kEnumValue1) && (s <= kEnumValue2)) {
2:   MyObject * o = [self findObjectFor:s];
3:   if ([o isValidFor:self]) {
4:     [arrayOfMyObjects removeObject:o];
5:     for (MyObject * mo in arrayOfMyObjects) {
6:       ...
7:     }
8:   }
9: }

For some really weird reason, when my code reaches line 4, if I step over, it goes back to the start of the method on the same thread, without going thru lines 5-. Does anybody have any clue why this happens?

removeObject on NSMutableArray does not mention any exception.

Are you debugging in debug configuration? Optimizations can make the flow of your code jumpy. — zneak
– zneak, Commented Feb 12, 2011 at 19:29
yes. I'm debugging with debug profile. The code is really called twice, because I raise an error when I try to find "s" and it does not exists. — Eduardo Costa
– Eduardo Costa, Commented Feb 12, 2011 at 19:45

bbum · Accepted Answer · 2011-02-12 20:00:28Z

2

It is safe to assume that you did not find a bug in removeObject: (unless you wrote your own).

Have you checked arrayOfMyObjects? Is it non-nil? Does it contain anything?

answered Feb 12, 2011 at 20:00

bbum

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1 Comment

Eduardo Costa Over a year ago

Yes, it was non-nil, contained only the removed instance

Eduardo Costa · Accepted Answer · 2011-02-12 21:08:22Z

1

OK, after lots of debugging in all classes on my project, I found that, when MyObject's release is called, it calls "release" on another class (since it is the last reference, it calls "dealloc"), once again for a third class, and then, it invokes removeObjectForKey:nil in NSMutableDictionary. This raises an NSInvalidArgumentException that is not logged at all. Way too evil...

answered Feb 12, 2011 at 21:08

Eduardo Costa

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2 Comments

bbum Over a year ago

Gotta love those. Think of how much you've grown as an iOS programmer by tracking that down. ;)

Eduardo Costa Over a year ago

Exact. I miss the time when understanding UITableView was my biggest problem. :D

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