How to insert row and section into UICollectionView at same time?

Question

In UITableViewController I can insert row and section at the same time with this implementations:

    func controllerWillChangeContent(controller: NSFetchedResultsController) {
        self.tableView.beginUpdates()
    }

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

        if controller == frc {

            switch(type) {
            case .Insert:

                self.tableView.insertRowsAtIndexPaths([newIndexPath], withRowAnimation: .Fade)

            case .Delete:

                self.tableView.deleteRowsAtIndexPaths([indexPath], withRowAnimation: .Fade)

            case .Update:

                self.tableView.reloadRowsAtIndexPaths([indexPath], withRowAnimation: .None)

            default:
                break
            }
        }
    }

    func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {

        switch(type) {
        case .Insert:
            self.tableView.insertSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
        case .Delete:
            self.tableView.deleteSections(NSIndexSet(index: sectionIndex), withRowAnimation: .Fade)
        default:
            break
        }
    }

    func controllerDidChangeContent(controller: NSFetchedResultsController) {
        self.tableView.endUpdates()
    }

What about UICollectionViewController? I haven't found alternative way to implement controllerWillChangeContent and controllerDidChangeContent.

Answer 1

collectionView works somewhat different than tableView, you need to use performBatchUpdates

var frc: NSFetchedResultsController?
var iip = [NSIndexPath]()
var dip = [NSIndexPath]()
var ins: NSIndexSet?
var des: NSIndexSet?

func controllerWillChangeContent(controller: NSFetchedResultsController) {
}

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

    if controller == frc {

        switch(type) {
        case .Insert:

            iip.append(newIndexPath)

        case .Delete:

            dip.append(indexPath)

        case .Update:

            self.collectionView!.reloadItemsAtIndexPaths([indexPath])

        default:
            break
        }
    }
}

func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {

    switch(type) {
    case .Insert:

        ins = NSIndexSet(index: sectionIndex)
    case .Delete:


        des = NSIndexSet(index: sectionIndex)
    default:
        break
    }
}

func controllerDidChangeContent(controller: NSFetchedResultsController) {

    self.collectionView!.performBatchUpdates({

        self.collectionView!.insertItemsAtIndexPaths(self.iip)
        self.collectionView!.deleteItemsAtIndexPaths(self.dip)
        if self.ins != nil {
            self.collectionView!.insertSections(self.ins!)
        }
        if self.des != nil {
            self.collectionView!.deleteSections(self.des!)
        }

        }, completion: {completed in

            self.iip.removeAll(keepCapacity: false)
            self.dip.removeAll(keepCapacity: false)
            self.ins = nil
            self.des = nil
    })
}