Question

I wrote a class, which acts as a filter. I pass three objects:

1. An NSArray, which holds objects to filter (these objects have a timestamp property)
2. An NSMutableArray (which will hold the section names for a tableView, the periods based on timestamps). I need this array, because I have to sort the periods.
3. An NSMutableDictionary, in which the keys will be the section names, the values are NSMutableArrays, which hold the items for a given period.

In the class from which I pass these objects, there is a tableView, in which I display the items.
This class has it own NSMutableArray and NSMutableDictionary, I not initialize them, only retain the corresponding return values of the filter class. In the delloc method I release them. There is a method in the filter class:

+ (void)insertItem:(id)item forPeriod:(NSString *)period toContainer:(NSMutableDictionary *)container {

    if ( ![[container allKeys] containsObject:period] ) {

        // the period isn't stored, create and store it
        NSMutableArray *periodArray = [[NSMutableArray alloc] init];
        [container setObject:periodArray forKey:period];
        [periodArray release];
        periodArray = nil;
   }

   // store the item
   NSMutableArray *arrayForPeriod = [container objectForKey:period];
   [arrayForPeriod addObject:item];
   arrayForPeriod = nil;
}

The instruments shows me leak when I set the newly allocated array as an object of the dictionary. At this point this is definitely true, because the dictionary retains again the array, so after the release, it retain count remains 1. But I think in the caller class when I release the dictionary, the array will be released too. Am I wrong?

Answer 1

Yes it is considered as a leak because your var is a local variable. Then you still have an object in memory but no reference to it. Remember the init makes a retain + the retain made by the dictionary = 2 retains. Just create your array using

NSMutableArray *periodArray = [[[NSMutableArray alloc] init]
autorelease]

Is it clear ?