On 31 May 2008, at 19:47, Rick Mann wrote:
Jonathan, thank you for the excellent example on working with the containers. That will certainly be useful.
You're welcome, but I apologise, I forgot the -rootNodes method that one of the tree controller methods I sent you calls! This method returns the top-level objects in the tree (NSTreeController.h assures me that -arrangedObjects responds to -childNodes, this differs from what the docs say).
// NSTreeController_Extensions
- (NSArray *)rootNodes;
{
return [[self arrangedObjects] childNodes];
}
now it'll work!.
On May 31, 2008, at 12:05:58, I. Savant wrote:1 - Create a fetch request for your desired entity.2 - Create a sort descriptor for the key whose max value you're interested in.3 - Set the fetch request's sort descriptor to the above.4 - Create any predicates needed for filtration (ie, whatever you may or may not have used in the tree controller).5 - Set the fetch request's predicate to the above if any.6 - Execute the fetch request and get the last (or first) object of the results (checking for errors, minding the set-versus-array gotchas, etc.).Wow, really? No way to just get at all the items in the tree controller with some key path, then use @max?
Think of this this way, only the tree controller knows which objects it has in it. The context and the model objects are ignorant of this. The entity you fetch is that you set in IB for the tree controller, so that is *kind of* asking the context, "get me the nodes in the tree controller", but not exactly as the tree controller itself may have a predicate that causes it to fetch only some of those types of entities. The fetch request (if you set the same predicate as the you have for the tree controller) will get you your NSSet of objects, then you can do whatever you want with the objects.
HTH, Jon
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