Question

So basically I have a huge array of arrays (only a 2-d array)…

My root array lets say has 100 child arrays…

I want to query the root/child arrays and return only the child arrays that have its 2 object equal to hello…

So basically I have a made-up idea below…

updatedArray = [rootArray WHERE childArray objectAtIndex:2 == @"hello"];

Now as you can see I want updated array to contain like 40 or 50 of the child arrays in the rootArray…

See what I mean – its kind of like MySQL only with an array instead of a database?

Answer 1

Try this:

NSMutableArray *updated = [[NSMutableArray alloc] init];
for (NSArray *a in rootArray)
{
    if ([[a objectAtIndex:2] isEqualToString:@"hello"])
        [updated addObject:a];
}

Now updated will contain the arrays in rootArray whose 3rd object is @"hello".

Don’t forget to release it after use (if you don’t use ARC).

You can also use predicates for simple logic; see the NSPredicate class.