Category object for incrementing all items in a mutable array

Hi guys, I was wondering how to add/increment certain ints within my NSMutableArray.

I have:

NSMutableArray *numbers = [[NSMutableArray alloc] init];
numbers[0] = @20;
numbers[1] = @40;
numbers[2] = @60;
NSLog(@"the numbers are %@",numbers);

So far I know that I can remove/add objects at a specific index, but lets say I would like to increase all the ints in my array by 2? And would also like to use the +2 increment to all items in the array for any other arrays in the future.

i know I would most probably have to make a new category object I'm also guessing that I'll need to use a for loop to traverse the array.

Which brings me to my question:

1 - how will I make sure that the for loop targets each individual array item, rather than add up the sum of all my array items(as shown in the earlier for loop video)?

Sorry if this as I'm still a bit hazy about categories, thanks! =)

Cheers

• mervin