Question

I try to write a program in Objective C that calculates some stuff. Unfortunately there is a lot to calculate and the Program is running a loop with 10000 iterations. The total running time is around 5 minutes.
This isn’t an issue but while it is running the memory the program uses goes up dramatically (above to 2GB) and I figure it is because of some Values that are not released. I narrowed the problem down to a creation of a NSArray inside a loop. The problematic code (changed it to concentrate on the problem) is this:

for (NSInteger k = 0; k<100000; k++) {

    NSMutableArray *mutableTestArray = [NSMutableArray new];
    for (NSInteger i=0; i<200; i++){

        NSMutableArray *subArray = [NSMutableArray new];
        for (NSInteger j=0; j<200; j++) {

            //simplified version, normally the valus for sub array are dependent on some other factors
            [subArray addObject:[NSArray arrayWithObjects:@"test", @"test", nil]];

        }
        [mutableTestArray addObject:subArray];

    }


    //do stuff with mutableTestArray
    //change parameters that go into sub array

}

If I replace:

[subArray addObject:[NSArray arrayWithObjects:@"test", @"test", nil]];

with:

[subArray addObject:@"test"];

it works fine. So I guess I somehow have to release the Array I created. But how?
I have ARC enabled and as far as I know if it is enabled I can’t release objects manually. It would be great if someone could help me with how to change the code or hint me somewhere where I can learn how to do memory management correctly.

Thanks

Answer 1

Just throw in some autoreleasepools :

@autoreleasepool {
        NSMutableArray *subArray = [NSMutableArray new];
        for (NSInteger j=0; j<200; j++) {
@autoreleasepool {

            //simplified version, normally the valus for sub array are dependent on some other factors
            [subArray addObject:[NSArray arrayWithObjects:@"test", @"test", nil]];
}
        }
        [mutableTestArray addObject:subArray];

}