Terminating app due to uncaught exception 'NSGenericException'

Question

I get this error once in a while when my program is running. Most of the time, the app works fine, but every now and then the app will crash and point to the second line in the for loop saying:

Terminating app due to uncaught exception 'NSGenericException', reason: '* Collection was mutated while being enumerated.'

for(int i = 1; i <= 121; i++) {
        NSLog(@"%i", i);
        [(UIButton *)[self.view viewWithTag:i] setImage:[UIImage imageNamed:@"hexagon"] forState:UIControlStateNormal];
}

What do I do to avoid my program from crashing??

Does you view has 121 uibuttons? – Himanshu Joshi Mar 08 '14 at 14:56 — Himanshu Joshi, Mar 08 '14 at 14:56
Please post the symbolicated crash report or stack trace. – Kerni Mar 08 '14 at 15:59 — Kerni, Mar 08 '14 at 15:59
yes my view has 121 buttons – user2905147 Mar 09 '14 at 08:22 — user2905147, Mar 09 '14 at 08:22

score 0 · Answer 1 · answered Mar 08 '14 at 15:04

0

You are trying to change items in an array while you are looping through the array.

Try making a copy of the subviews to loop through so you can change the original.

NSArray *loopingArray = [self.view.subviews copy];

for (int i = 0; i < [loopingArray count]; i++){

    NSLog(@"%i", i);
    if ([self.view viewWithTag:i])
        [(UIButton *)[self.view viewWithTag:i] setImage:[UIImage imageNamed:@"hexagon"] forState:UIControlStateNormal];
}

answered Mar 08 '14 at 15:04

digitalHound

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Where is he looping through the array? Isn't he just using a regular for loop? – Corb3nik Mar 08 '14 at 15:08
Good call, I missed that. It could be that the system is enumerating the subviews when he happens to change one of them. – digitalHound Mar 08 '14 at 15:17
All I need to do is change the picture for the buttons with the tag i. – user2905147 Mar 08 '14 at 22:48

Terminating app due to uncaught exception 'NSGenericException'

1 Answers1