***SOLVED*** Re: NSArrayController Managing / Sorting NSManagedObjects
I found some sample code that addresses this:
http://shanecrawford.org/2008/37/sorting-a-coredata-backed-nsarraycontroller/
On Aug 7, 2009, at 2:50 PM, Brad Gibbs wrote:
> Hi, > > I have an NSTableView that displays a set of Activity objects, which > are subclasses of NSManagedObject, all of which are managed by a > custom NSArrayController. Each Activity has a sortIndex property, > which is used to… wait for it… sort the activities. > > The array controller adds logic to update the sortIndex as objects > are added, removed or re-ordered. It’s this last part that’s giving > me grief. The table supports drag-and-drop. The idea is that when > an Activity is dragged up or down in the list, the sortIndex for all > of the activities get updated, so that the next time the list of > activities is displayed, the activities maintain the order in which > they were placed by the user. > > The array controller’s sort descriptors binding is bound to an array > with a single NSSortDescriptor, set to order the objects by > sortIndex. I think this is causing some grief. Also, the code that > assigns new sortIndexes for each object calls [arrayController > arrangedObjects] to get the array controller’s objects. From my > reading of the documentation, this calls arrangeObjects on the > underlying array, which I don’t really want to do until all of the > Activity objects’ sortIndexes have been updated to reflect their new > positions in the array. > > The objects that are dropped are assigned new sortIndexes based on > their new indexes immediately after being dropped into the array. > I’m not doing anything with the sortIndexes for the items in the > array that haven’t been moced until later. In the interim, I > believe that calling [arrayController arrangedObjects] is trying to > make the NSArrayController arrange its objects based on its sort > descriptor (sortIndex), while one or more of the objects in the set > share the same sortIndex. This is causing problems. > > I’m hoping someone can point me to some sample code that addresses > this issue. I’ve looked at Demo Monkey and a couple of other > samples I found on the web without being enlightened. Jonathan Dann > has sample code using sortIndex and an NSTreeController, but > updating the treeController doesn’t involve rearranging its items > first, so, it doesn’t quite work. > > Possible solutions I can see: > > 1. manually assigning new sortIndexes to all objects from the point > of insertion through the end of the array / set immediately upon > insertion of the moved objects, or: > 2. copying the entire array after insertion and then using the > copied array to assign new indexes: > > for (Activity *anActivity in activitiesArrayCopy) { > [anActivity setValue:[NSNumber numberWithInt:[activitiesArrayCopy > indexOfObject:anActiviity]] forKey:@”sortIndex”] > } > > But, I think there’s a cleaner, more elegant solution out there that > I’m not seeing. > > Any suggestions would be appreciated. > > > Thanks. > > Brad > > > _______________________________________________ > > > > http://lists.apple.com/mailman/options/cocoa-dev/bradgibbs%40mac.com > > This email sent to bradgibbs@mac.com