Problem with arrays (add and copy)

Question

I've got a problem. I'm trying to sort the items from 1 array (name: mps) into an other array (name: totalArray), but every item should be in a new array. In short: the items in mps should move into a new array, but every item should be in a new array, so the totalArray is an array of arrays. After that, totalArray should be copied back into mps.

To clarify, here is the code:

NSMutableString *oud = [[NSMutableString alloc] init];
NSMutableString *nieuw = [[NSMutableString alloc] init];
NSMutableArray *tempArray = [[NSMutableArray alloc] init];
[tempArray removeAllObjects];
NSMutableArray *totalArray = [[NSMutableArray alloc] init];
[totalArray removeAllObjects];
tempArray = [[NSMutableArray alloc] init];
[tempArray removeAllObjects];
for (int j = 0; j < [mps count]; j++)
{
    nieuw = [[mps objectAtIndex:j] valueForKey:@"ConfigurationAlias"];
    if (j != 0)
    {
        if ([oud rangeOfString:nieuw].location == NSNotFound) 
        { 
            NSLog(@"ADDED!");
            [totalArray addObjectsFromArray:tempArray];
            [oud setString:nieuw];
            [tempArray removeAllObjects];
            [tempArray addObject:[mps objectAtIndex:j]];
        }
        else
        {
            [tempArray addObject:[mps objectAtIndex:j]];
        }
    }
    else {
        [oud setString:nieuw];
        [tempArray addObject:[mps objectAtIndex:j]];
    }
}

//En de array weer laden in de tabel
//NSLog(@"%@", totalArray);
NSLog(@"%i", [mps count]);
[mps removeAllObjects];
NSLog(@"REMOVED!!!");
NSLog(@"%i", [mps count]);
[mps addObjectsFromArray:totalArray];
NSLog(@"Added totalArray: %i", [totalArray count]);
NSLog(@"%i", [mps count]);
[tempArray release];
[totalArray release];
[tabelView reloadData];

}

Now, here comes my problem:

The log gives the line 2011-04-07 10:02:46.368 Fleet Manager[901:40b] ADDED! 11 times, then it posts 16 (mps count, this is correct), then the line REMOVED!, then 0 (mps count, also correct), but then the line: Added totalArray: 15. This can't be correct, it added 11 times but it counts 15?

This a problem for me, in the first place because it's plain incorrect, but the tableview gets screwed up as well because of the section-amount not being correct either (15 sections). Anybody has any idea what's going on?

EDIT: all the objects in mps are dictionaries, and all of them have a value for the key "ConfigurationAlias".

Ziggy · Accepted Answer · 2011-04-07 08:36:07Z

1

First, I would like to suggest using debugging mode instead of bunch of NSLog functions to track down what's actually happening inside your objects and variables. Try using breakpoints. Set one for [totalArray addObjectsFromArray:tempArray]; line so every time this line of code is reached the execution would stop and let you look around, check different fields' states inside totalArray and tempArray objects.

Concerning your problem... Since you are using addObjectsFromArray: that means that passed array may pass not one but several objects (thus the plural in method name). I guess one of those "11 times" added more than one element - that should explain the actual count being more than the times you've called this method. Again, please check tempArray contents.

Good luck!

answered Apr 7, 2011 at 8:36

Ziggy

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Joetjah Over a year ago

ah, I narrowed it down. I need sleep so badly. It shouldn't be addObjectsFromArray, but addObject. Tjeez. Ah well, I got a tad further now :) Now it loads the table, but with the same object everytime. But that's one for the next time ;)

z00b · Accepted Answer · 2011-04-07 08:38:23Z

If you want to end up with an array of arrays, you need to be allocating temp arrays inside the loop. It also seems like you are overdoing it with clearing out the arrays.

It appears you are trying to add the value from mps to totalArray regardless of the conditions, so it would make sense to only do that in one place (outside of the conditions).

Also, if you are not mutating the arrays (such as tempArray), you can use NSArray instead, which should be smaller and faster.

Finally, you should be able to assign the new array to mps instead of doing the expensive array copying. Not sure if that is somehow referenced as the table delegate, though.

I would try something like:

NSMutableString *oud = [[NSMutableString alloc] init];
NSMutableString *nieuw = [[NSMutableString alloc] init];

NSMutableArray *tempArray;

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

for (int j = 0; j < [mps count]; j++)
{
    tempArray = [[NSMutableArray alloc] init];
    [totalArray addObject:tempArray];
    [tempArray release];

    nieuw = [[mps objectAtIndex:j] valueForKey:@"ConfigurationAlias"];

    if (j != 0)
    {
        if ([oud rangeOfString:nieuw].location == NSNotFound) 
        { 
            NSLog(@"ADDED!");
            [oud setString:nieuw];
        }
    }
    else {
        [oud setString:nieuw];
    }
}

NSLog(@"%i", [mps count]);
[mps removeAllObjects];

NSLog(@"REMOVED!!!");
NSLog(@"%i", [mps count]);

[mps addObjectsFromArray:totalArray];
NSLog(@"Added totalArray: %i", [totalArray count]);
NSLog(@"%i", [mps count]);

[totalArray release];
[tabelView reloadData];
}

Stefan Ticu · Accepted Answer · 2011-04-07 08:18:38Z

0

You should

sort the base array in a tempArray
create an empty resultArray
iterate through tempArray and for each item create an itemArray containing the item on the first position and add this array to resutArray
don't forget to release all alloc-ed temporary data

Check this out for sorting easily: Sorting arrays via Apple

answered Apr 7, 2011 at 8:18

Stefan Ticu

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1 Comment

Joetjah Over a year ago

the array is sorted on ConfigurationAlias, but there are 3/4 items which have the same CA-value, meaning they both have to be in 1 array. Say the resultarray should looks like this format: [ [0], [1], [2,3], [4] ] in which item 2 and 3 have the same CA-number.

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