Autoreleased NSMutableArray not populated

Question

I want to populate an array like this:

NSMutableArray *array = [self methodThatReturnsAnArray];

In the "methodThatReturnsAnArray"-method I create an array like this:

NSMutableArray *arrayInMethod = [[NSMutableArray alloc] init];

When I'm finished populating "arrayInMethod" I'm returning the array and in order to prevent a memory leak I'm using:

return [arrayInMethod autorelease];

However the "array"-variable is never populated. When removing the "autorelease" it works fine though. What should I do in order to make sure that the returned object i released?

EDIT

+ (NSMutableArray *)buildInstants:(NSArray *)huntsArray {

    NSMutableArray *goGetObjects = [[[NSMutableArray alloc] init] autorelease];

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

        NSDictionary *huntDict = [huntsArray objectAtIndex:i];

        PHGoGet *goGet = [[PHGoGet alloc] init];

        goGet.title = [huntDict objectForKey:@"title"];
        goGet.description = [huntDict objectForKey:@"description"];
        goGet.start = [huntDict objectForKey:@"start"];
        goGet.end = [huntDict objectForKey:@"end"];
        goGet.ident = [huntDict objectForKey:@"id"];

        if ((CFNullRef)[huntDict objectForKey:@"image_url"] != kCFNull) {

            goGet.imageURL = [huntDict objectForKey:@"image_url"];

        } else {

            goGet.imageURL = nil;
        }

        if ((CFNullRef)[huntDict objectForKey:@"icon_url"] != kCFNull) {

            goGet.iconURL = [huntDict objectForKey:@"icon_url"];

        } else {

            goGet.iconURL = nil;
        }

        goGet.longitude = [huntDict objectForKey:@"lng"];
        goGet.latitude = [huntDict objectForKey:@"lat"];
        goGet.companyIdent = [huntDict objectForKey:@"company_id"];

        [goGetObjects insertObject:goGet atIndex:i];
        [goGet release];
    }

    return [[goGetObjects copy] autorelease];
}

Answer 1

Try using the convienence method for NSMutableArray... change:

NSMutableArray *arrayInMethod = [[NSMutableArray alloc] init];

To...

NSMutableArray *arrayInMethod = [NSMutableArray array];

array will return an autoreleased object.

Answer 2

First of all, I recommend you not to return a NSMutableArray from any method. It's better to use NSArray for that to avoid some very difficult to debug problems. My proposition is:

You declare the mutable array and populate it:

NSMutableArray *arrayInMethod = [[[NSMutableArray alloc] init] autorelease];

Then you return an autoreleased copy:

return [[arrayInMethod copy] autorelease];

And finally, when you take the returned array, you make it mutable again (only if you need to change it):

NSMutableArray *array = [[self methodThatReturnsAnArray] mutableCopy];

When you're done with the array, you release it:

[array release];