Question

I have a memory leak when i call a method that return me a string—-
the method definition is as follows

-(NSMutableArray *)read
{
NSMutableArray  *dataArray = [[NSMutableArray alloc] init];

//picking data from database here


return dataArray;
}

this show a big memory leak
i also tried— NSMutableArray *dataArray = [[[NSMutableArray alloc] init]autorelease];

but this time leack checking process gets hanged

i also cannot release that array before return

please help

Answer 1

-(NSMutableArray *)read
{
    NSMutableArray  *dataArray = [[NSMutableArray alloc] init];

    //picking data from database here

    return dataArray;
}

Anything that uses the method read will expect to get back an object it does not own. However, as written here, dataArray is still owned at the point of return. You can’t release it because that might make it go away altogether. You must, in this instance autorelease the array. You can either do this:

-(NSMutableArray *)read
{
    NSMutableArray  *dataArray = [[[NSMutableArray alloc] init] autorelease];

    //picking data from database here

    return dataArray;
}

or this

-(NSMutableArray *)read
{
    NSMutableArray  *dataArray = [[NSMutableArray alloc] init];

    //picking data from database here

    return [dataArray autorelease];
}

You say “leak checking process get hanged” but I’m really not sure what you mean by that. Whether it hangs, crashes or plays the Botswana National Anthem, you definitely need to autorelease the returned array and any other problem is actually a different problem. Possibly, you are forgetting to retain the data elsewhere.