How do I check if an object exists at a certain index of an NSMutableArray?

Question

For instance, how could I verify if there is an item at the index 3? The objects in the `NSArray` are instantiated from the class "Animal."

Accepted Answer

Well, since `NSMutableArray` has to hold non-nil objects, as long as the array is big enough, you know there's something at index `i`:

```
if ([myArray count] > 3) {
    id myObj = [myArray objectAtIndex:3];
    ...
}
```

If you needed to check something elsek, like say make sure it didn't have a reference to the NSNull singleton, you could then check

```
if (myObj != [NSNull null]) ...
```

Solution