iPhone ... If you have an NSArray of NSMutableDictionaries, does the Array hold a ref to the dict or a "copy"?

Question

Okay, coming from a perl background I am used to Arrays holding refs to Hashes (Dictionary in iPhone parlance).

What I would like to know is this: If I have a NSArray of NSMutableDictionaries. Say I added the following NSMutableDictionary to an NSArray:

[theArray addObject:[[NSMutableDictionary alloc] initWithObjectsAndKeys: timestamp, @"timestamp" ,name, @"name" ,lat, @"lat" ,lon, @"lon" , nil]];

Then later I cycled through the array like so:

for (NSMutableDictionary theDict in theArray)
{

}

does each theDict represent a pointer NSMutableDictionary's data such that I can do this:

for (NSMutableDictionary *theDict in theArray)
{
      if ([theDict objectForKey:@"timestamp"] != nil && [[theDict objectForKey:@"timestamp"] isEqualToString:@"timestamp"])
      {
           [theDict setObject:@"new name" forKey@"name"];
      }   
}

and then expect theArray to hold the changed value throughout the life of theArray?

or, do I need to do this:

int ct = 0;
for (NSMutableDictionary *theDict in theArray)
{
      if ([theDict objectForKey:@"name"] != nil && [[theDict objectForKey:@"name"] isEqualToString:@"name you want to change"])
      {
           NSMutableDictionary *tmpDict = [[NSMutableDictionary alloc] initWithDictionary:theDict copyItems:YES];
           [tmpDict setObject:@"new name" forKey@"name"];
           [theDict replaceObjectAtIndex:ct withObject:tmpDict];
           [tmpDict release];
           break;
      }
      ct += 1;
}

It cannot be all that code, can it? -- just to replace one value for a key of a NSMutableDictionary held in an NSArray?

Sorry if this question is obvious to some...but still trying to wrap my mind around pointer to a dictionary (or object) in Objective-c -- with is roughly equivalent to a ref to a hash in perl -- vs a copy (or deepcopy) of an object in Objective-c. And the problem is made more confusing by the NSArray holding the pointers (hopefully) to the NSMutableDictionaries. This is how it is done in perl -- and from what I am understanding -- outside of the name (pointer vs reference) .. it is the same in Objective-c.

Answer 1

You should do it the first way. Each theDict is a pointer to the original, not a copy.

Edit: remainder of answer no longer relevant following edit of question, but left around to give context to comments and because you can never have too many links to the object ownership docs!

---

Your autorelease vs release aside suggests a possible misunderstanding about something else, but this perhaps isn't the time to go into that in detail. I suggest you have another look at the object ownership docs to be sure you understand what autorelease really means.

(Btw, your initial tmpArray should be theArray I think, unless I've totally misunderstood your question. And the type of the loop variables should be NSMutableDictionary* rather than NSMutableDictionary.)