CODEWITHSUNDEEP
iosuitableviewcore-datansfetchedresultscontroller
János
János

Reputation: 35038

How to implement NSFetchedResultsController delegate when multiple row is on deletion?

Two items is deleted.

func controller(controller: NSFetchedResultsController!, didChangeObject anObject: AnyObject!, atIndexPath indexPath: NSIndexPath!, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath!) {

    switch(type) {
    case .Delete:

        tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)
    default:
        break
    }
}

At deletion line I get this error:

CoreData: error: Serious application error. Exception was caught during Core Data change processing. This is usually a bug within an observer of NSManagedObjectContextObjectsDidChangeNotification. Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (0) must be equal to the number of rows contained in that section before the update (2), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out). with userInfo (null)

*** Terminating app due to uncaught exception 'NSInternalInconsistencyException', reason: 'Invalid update: invalid number of rows in section 0. The number of rows contained in an existing section after the update (0) must be equal to the number of rows contained in that section before the update (2), plus or minus the number of rows inserted or deleted from that section (0 inserted, 1 deleted) and plus or minus the number of rows moved into or out of that section (0 moved in, 0 moved out).'

Upvotes: 1

Views: 424

Answers (1)

Mike Pollard
Mike Pollard

Reputation: 10195

You need to 'batch' the updates by also implementing the controllerWillChangeContent and controllerDidChangeContent delegate methods as follows (although sorry these are Obj-c):

- (void)controllerWillChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView beginUpdates];
}

- (void)controllerDidChangeContent:(NSFetchedResultsController *)controller {
    [self.tableView endUpdates];
}

Upvotes: 2

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