Question

working with a basic objective c example here, tried to use replaceObjectAtIndex for an array and it doesn’t seem to be working.

my code:

 NSMutableArray *myArray=[NSMutableArray array];
    [myArray addObject:@"First string"];
    [myArray addObject:@"Second string"];
    [myArray addObject:@"Third string"];

    NSString *newElement=[myArray objectAtIndex:1];
    NSLog(@"New object at index 1 BEFORE is %@", newElement);
    [myArray replaceObjectAtIndex:1 withObject:@"Hello"];
    NSLog(@"New object at index 1 AFTER is %@", newElement);

theoretically the output for newElement should now display “Hello”, but it’s still displaying “Second String”

output:

2012-05-30 11:21:16.638 cocoa lab[753:403] New object at index 1 BEFORE is Second string
2012-05-30 11:21:16.641 cocoa lab[753:403] New object at index 1 AFTER is Second string

please advise

thank you

Answer 1

You need to get the new value from the array after replacing it

// ...
[myArray replaceObjectAtIndex:1 withObject:@"Hello"];

/* ADD THIS */
newElement=[myArray objectAtIndex:1];

NSLog(@"New object at index 1 AFTER is %@", newElement);

At the moment you fetch the original string, replace the array’s object, and print out the original string again.