Question

I can create an NSArray that contains all the hash values of the objects in myArray like this:

NSArray *a = [myArray valueForKey:@"hash"];

What key do I pass to valueForKey: to get an array containing myArray’s indices?

Say myArray has n items. I’d like to do something like this:

NSArray *a = [myArray valueForKey:@"index"];

Answer 1

NSArray * arrayWithNumbersInRange( NSRange range )
{
    NSMutableArray * arr = [NSMutableArray array];
    NSUInteger i;
    for( i = range.location; i <= range.location + range.length; i++ ){
        [arr addObject:[NSNumber numberWithUnsignedInteger:i];
    }

    return arr;
}

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NSArray * indexArray = arrayWithNumbersInRange((NSRange){0, [myArray length]-1});