Copy specific index value of array to another array?

Question

I am trying to copy a specific values at specific index from one array to another like this:

for (int i = 0; i < 100; i++) {
        if ([subID[i]  isEqual: @"0"]) {
            NSLog(@"state : %@",arrayTempState[i]);
            NSString *str = arrayTempState[i];
           [arrayState addObject:str];
            NSLog(@"%@",arrayState[i]);

 }

arrayState is NSMutableArray and arrayTempState is NSArray

but arrayState is null every time.

I tried arrayState[i] = arrayTempState[i]; but it did not work.

Answer 1

arrayState was not initialised that is why it couldn't store the value.