Memory leak, nsmutablearray and custom object

Question

I have tried to search for similar problems, but not found any good solutions. So I hope someone can help me.

Basically I have a leak in this method that populates an Array with Card objects (the tempArray is created and populated above this loop):

for(int i = 0; i < numberOfCards; i += 2) {
    int randomNumber = (arc4random() % [tempArray count]);
    NSNumber *number = [tempArray objectAtIndex:randomNumber];
    [tempArray removeObject:number];

    Card *card1 = [[Card alloc] initWithCategory:category andNumber:[number intValue]];
    Card *card2 = [[Card alloc] initWithCategory:category andNumber:[number intValue]];

    [number release];

    [cards addObject:card1];
    [cards addObject:card2];
}

The method does contain a little more logic, but I am pretty sure this loop contains the leak. When I run it with Instruments I see that the Card objects does not get released. In the dealloc method I do release the array, I thought this would also release the objects inside the Array?

-(void) dealloc {
    [cards release];

    [super dealloc];
}

I have tried autorelease on card1 and card2, tried to make them class variables. But nothing seems to help. Either I have the leak or if I try to add a release on the card1 or card2 the application crashes. Anyone have an idea what is wrong here?

N.B. you should not release number since you do not own it. — albertamg
– albertamg, Commented Jul 29, 2011 at 17:57

Man of One Way · Accepted Answer · 2011-07-29 17:34:08Z

2

You need to release each Card object after you have added them to cards. When adding them to cards the retain count of each object automatically increases. Therefore add:

[card1 release];
[card2 release];

after

[cards addObject:card1];
[cards addObject:card2];

answered Jul 29, 2011 at 17:34

Man of One Way

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4 Comments

Jarle Hansen Over a year ago

Thanks, that makes sense. However, it does crash now in the dealloc method, when I call [cards release]; Not sure why.

Man of One Way Over a year ago

Look for all places in code where you either say [cards retain];, cards = [[NSAMutable alloc] ..]; and then all places where you say [cards release]; They should cancel each other out.

Jarle Hansen Over a year ago

Finally I got it working, thanks for the help. One thing I dont understand thought, in the card object had two properties. When I changed the settings from image=... and text=... to self.image= and self.text= it worked. Do you know why?

Man of One Way Over a year ago

Yes, when you use self.property = .., you are using the setter function, in there it automatically retains the value you are setting. However, if you are only saying property = .. the getter is not called and you have to retain yourself. You can try this by removing self. and instead add image = [.. retain];

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