Question

I have this code:

secondArray = [firstArray objectAtIndex:1];

The object at index 1 is already an NSMutableArray inside [firstArray]. The problem is that when I change secondArray, the firstArray also changes.

How can I stop this?

Answer 1

The best way to keep it from changing is to copy the array instead of set it. I had that problem before, and this is what did the trick for me

EDIT: just so I don’t give you poor information, I’m going to change this to a more generalized version:

NSMutableArray *secondArray = [NSMutableArray alloc] initWithCapacity:[[firstArray objectAtIndex:1] count];
[secondArray addObjectsFromArray:[firstArray objectAtIndex:1]];

This should better fit your situation. I have tested it twice to be sure by creating arrays and cloning them, then modifying the clones to see they are the only objects being modified