Objective-C memory management (alloc and autorelease)

Question

When you allocate and initialize and object, and then want to return that object, how are you supposed to return it?

I have the following code:

NSXMLDocument* fmdoc = [[NSXMLDocument alloc] initWithContentsOfURL:trackInfoUrl options:NSXMLDocumentTidyXML error:&err];
return [fmdoc autorelease];

Is this correct?

Answer 1

That is correct. Since you are initializing the object, it is your responsibility to release or autorelease it.

As the retain count on creation is 1 and you want it to not be deleted before the calling method has a chance to use the object, autorelease is the correct message to send.

If you had sent it release, the memory would have been reclaimed immediately. By sending it autorelease the memory will not be reclaimed until the default autorelease pool is drained, which won't happen until after the calling method has had a chance to retain the object if it needs to.