NSFetchedResultsController order not changed when it should

I have a NSFetchedResultsController (or NSFRC) that is really pretty standard;

No predicate set

Fetch all items of one entity kind

Sorted by a NSDate field (descending)

Delegate is set

Data is fetched

Up next the data gets updated:

A background thread updates the data

the field used in the sort order gets changed among with other fields.

The changes are merged into the main threads' ObjectContext

The NSFRC nicely passes on the changes to the TableView, except for the order changes .

Is doesn't matter if I animate changes, or simply do reloadData() , data is changed, the order isn't.

I would expect the delegate for example to swap the first and second row because the second row's date value is now higher than the first one.

If I re-open the ViewController (so the fetch is done again on a new VC and NSFRC ) the order does change as expected. But thats anything but intuitive for the user.

Could anyone please point me into possible places to search for my mistake?

Just to reiterate:

Changes to content are being delegated, ie another field contains text, which does get changed.

The order is not being changed. So it appears the SortOrder is only used when fetching the very first time.

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Here's two screenshots, the second line (date) is also the sort order. The second image shows updated data but a wrong sort order.

Before

After

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When your data changes you may need to nil the NSFRC and let it do its thing. For example. Lets say that you have a function which changes the order of your items. If you are using standard Apple code, you should have something like this

func updateSort () {

    _fetchedResultsController = nil //Here is the magic
    tableView.reloadData()
}

// MARK: - Core Data
var fetchedResultsController:NSFetchedResultsController {
    if _fetchedResultsController != nil {
        return _fetchedResultsController!
    }

    // do your basic initialization and set the delegate and return it

    return _fetchedResultsController!

}

 var _fetchedResultsController: NSFetchedResultsController? = nil

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