Autorelease pool and memory management

I'm using the following function to put each "facility" node of my XML in a NSMutable array:

-(void) grabXML {

    NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];

    CXMLDocument *doc = [[[CXMLDocument alloc] initWithData:data options:0 error:nil] autorelease];

    NSArray *nodes = [[doc rootElement] nodesForXPath:@"//facilities" error:nil];

    for (CXMLNode *itemNode in nodes)
    {               
        for (CXMLNode *eventNode in [itemNode children])
        {           
            if ([[eventNode name] isEqualT开发者_开发百科oString:@"facility"]) {

                [content addObject:[eventNode copy]];               

            }

        }
    }

    loading = FALSE; 
    [table reloadData];

    [pool release];

}

Note that the pool is necessary, 'cause i call the grabXML method in a separate thread.

Using instruments i can see that the following line generates a leak

[content addObject:[eventNode copy]];

And if i change it to

[content addObject:eventNode];

i'm not able to access the XCMLNode later (it seems to be null).

I can avoid the leak putting this on my dealloc method:

for (CXMLNode *node in content) {
    [node release];
}

But i think i'm doing something wrong... or at least i'm not aware of what's going on... Please can you give me a clue?

Thanks!

copy creates an object with a retain count of 1, -addObject: adds an additional retain, so you have to either release eventNode after adding it to the array or autorelease the copy:

[content addObject:[[eventNode copy] autorelease]];

You should use

CXMLNode *tempEventNode =  [eventNode copy];
  [content addObject:tempEventNode];   
  [tempEvent release];

instead of , [content addObject:[eventNode copy]];

As when you are using [eventNode copy] it makes retaincount +1 and when you add this copy directly(as in your code) you are increasing it again by +1 as array will retain it. so for arrays retain its not your reponsibility to release but for your copy call you must release it.

[eventNode copy] --> retain count +1
[content addObject:[eventNode copy]]; -> retaincount +2

Thanks