On Mar 3, 2010, at 3:39 PM, Eli Bach wrote:
> I have a core-data app, with a view that shows a managed object, along with
> an NSCollectionView displaying related managed objects in 1 column, all
> hooked together primarily with bindings.
>
> This works fine (selecting different objects automatically updates the
> collectionview and I can add/edit/delete related objects).
>
> However, I would like to present the related records in the same order each
> time, as well as have new objects appear in a predicable location (namely, at
> one 'end' of the collectionview. I have an 'order' attribute, with
> NSInteger16 values, that I want to sort on.
>
> Just adding a NSSortDescriptor to the NSArrayController that the
> NSCollectionView gets it's managed objects from only partially works:
>
> 1) it ONLY does the sort if I have a button that changes the sort AFTER the
> array is fully populated. Setting the sortDescriptor on the
> NSArrayController when the view loads, or even as the root managed object is
> changed, doesn't result in the collectionview being sorted
>
> 2) adding or deleting a related record [removing/adding objects for the
> collectionview] randomizes the order of the objects presented in the
> collectionview [either by calling add: on the NSArrayController or directly
> creating a new NSManagedObject for the relation]. The object is
> presented/removed, but the order is always rearranged randomly.
>
> I've even tried (programmatically):
> -add/delete record
> -clear sort descriptor
> -set sort descriptor
>
> and it does do the sort. It only applies the sort if I hit a button that
> changes the sortDescriptor on the NSArrayController AFTER the collectionview
> gets fully populated.
>
> Any ideas on the best way to keep the nsarraycontroller and/or the
> nscollectionview sorted all the time?
To follow up on this, I've found what seems to be a stupid 'solution' to this,
namely subclass NSArrayController and override one method with this:
- (NSArray *)arrangeObjects:(NSArray *)objects
{
NSArray * returnValue = objects;
NSArray * sortDescriptors = [self sortDescriptors];
if ((sortDescriptors != nil) && ([sortDescriptors count] > 0))
{
returnValue = [objects
sortedArrayUsingDescriptors:sortDescriptors];
}
else
{
returnValue = [super arrangeObjects:objects];
}
return returnValue;
}
This results in the collectionview being sorted.
But I expected the arraycontroller to do this automatically just by setting
sortdescriptor, and perhaps setAutomaticallyRearrangesObjects:YES, on the
arraycontroller, but it doesn't seem to reliably apply the sort by itself.
Am I misunderstanding NSArrayController, or binding the collectionview to the
wrong part [it's bound to arrangedObjects], or a bug in NSArrayController?
Eli
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