Core Data: How to update an NSArrayController immediately after adding an NSManagedObject?

Question

I am adding an instance in core data. The entity is represented by an NSArrayController. I would like to access the newly added instance through the controller.

A "Skill" instance is added and then I try to access it through selectAddedObject as follows:

-(void)addSkill
{
    [self selectAddedObject:[NSEntityDescription insertNewObjectForEntityForName:@"Skill"
                                                          inManagedObjectContext:self.managedObjectContext]];
}

- (void)selectAddedObject:(NSManagedObject *)addedMO
{
    [self.sectionArrayController setSelectedObjects:[NSArray arrayWithObject:addedMO]];
    NSLog(@"Selected: %@", [self.sectionArrayController valueForKey:@"selectedObjects"]);
}

This only seems to work if I add

[self.managedObjectContext processPendingChanges];

as the first line of selectAddedObject:. But once I do that, the document seems to forget that it still needs to save, and I could quit the app without my addition being auto-saved. Don't want to force that onto the users!

Any ideas on a way to immediately update the array controller in some other way? Or perhaps to add the object in another way? A few earlier answers (e.g. Updating NSTableView when enitiy is added to core data) seem a bit outdated due to changes in OSX.

Thanks!!

Did you got any solution for this issue? – Parag Bafna Feb 06 '19 at 05:46 — Parag Bafna, Feb 06 '19 at 05:46

score 1 · Answer 1 · answered May 14 '13 at 20:58

1

Use the array controller to add the object. At some point during configuration, ensure the entity is set ([self.sectionArrayController setEntityName:@"Skill"]) and then do all of your work to create and select:

- (void)createAndSelectNewObject
{
    Skill *addedMO = [self.sectionArrayController newObject];

    if([self.sectionArrayController commitEditing]) {

        [self.sectionArrayController setSelectedObjects:[NSArray arrayWithObject:addedMO]];
        NSLog(@"Selected: %@", [self.sectionArrayController valueForKey:@"selectedObjects"]);
    }
}

You should commit any edits before changing the selection too (and only change the selection if the edits were committed or there weren't any).

answered May 14 '13 at 20:58

Wain

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Thanks, it looks very elegant this way. I do have a problem after trying this solution: `self.sectionArrayController` still has an unchanged number of objects after the commit! But the returned value is `YES`. Hmmm.... – Carelinkz May 15 '13 at 20:54
Just using `add:` on the array controller (in IB) also does not select the new object, not even with "Select inserted objects" checked in the interface builder. – Carelinkz May 15 '13 at 21:01
1

What does work, is adding `[self.managedObjectContext processPendingChanges];`. I would really like to do without. Is there are reason why `-commitEditing` does not work, and `-processPendingChanges` does? – Carelinkz May 15 '13 at 21:17
Although Wain's answer is a much more elegant way of accomplishing what I did in my code, I still have not found a way to avoid processPendingChanges. Does anyone have a further suggestion? – Carelinkz May 17 '13 at 19:46

Core Data: How to update an NSArrayController immediately after adding an NSManagedObject?

1 Answers1

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