This makes any UICollectionViewController able to handle an NSFetchedResultsController

UICollectionViewController+NSFetchedResultsController.swift

extension UICollectionViewController: NSFetchedResultsControllerDelegate {
    
    private struct AssociatedKeys {
        static var operationsArray = "operationsArrayKey"
    }
    
    var fetchedResultsProcessingOperations: [NSBlockOperation]? {
        get {
            return objc_getAssociatedObject(self, &AssociatedKeys.operationsArray) as? [NSBlockOperation]
        }
        
        set {
            if let newValue = newValue {
                objc_setAssociatedObject(
                    self,
                    &AssociatedKeys.operationsArray,
                    newValue as [NSBlockOperation]?,
                    .OBJC_ASSOCIATION_RETAIN_NONATOMIC
                )
            }
        }
    }
    
    private func addFetchedResultsProcessingBlock(processingBlock:(Void)->Void) {
        fetchedResultsProcessingOperations?.append(NSBlockOperation(block: processingBlock))
    }
    
    func controller(controller: NSFetchedResultsController, didChangeObject anObject: AnyObject, atIndexPath indexPath: NSIndexPath?, forChangeType type: NSFetchedResultsChangeType, newIndexPath: NSIndexPath?) {
        
        switch type {
        case .Insert:
            addFetchedResultsProcessingBlock {self.collectionView?.insertItemsAtIndexPaths([newIndexPath!])}
        case .Update:
            addFetchedResultsProcessingBlock {self.collectionView?.reloadItemsAtIndexPaths([indexPath!])}
        case .Move:
            addFetchedResultsProcessingBlock {
                // If installsStandardGestureForInteractiveMovement is on
                // the UICollectionViewController will handle this on its own.
                guard !self.installsStandardGestureForInteractiveMovement else {
                    return
                }
                self.collectionView?.moveItemAtIndexPath(indexPath!, toIndexPath: newIndexPath!)
            }
        case .Delete:
            addFetchedResultsProcessingBlock {self.collectionView?.deleteItemsAtIndexPaths([indexPath!])}
        }
        
    }
    
    func controller(controller: NSFetchedResultsController, didChangeSection sectionInfo: NSFetchedResultsSectionInfo, atIndex sectionIndex: Int, forChangeType type: NSFetchedResultsChangeType) {
        
        switch type {
        case .Insert:
            addFetchedResultsProcessingBlock {self.collectionView?.insertSections(NSIndexSet(index: sectionIndex))}
        case .Update:
            addFetchedResultsProcessingBlock {self.collectionView?.reloadSections(NSIndexSet(index: sectionIndex))}
        case .Delete:
            addFetchedResultsProcessingBlock {self.collectionView?.deleteSections(NSIndexSet(index: sectionIndex))}
        case .Move:
            // Not something I'm worrying about right now.
            break
        }
        
    }
    
    func controllerDidChangeContent(controller: NSFetchedResultsController) {
        collectionView?.performBatchUpdates({ () -> Void in
            self.fetchedResultsProcessingOperations?.forEach { $0.start() }
        }, completion: { (finished) -> Void in
            self.fetchedResultsProcessingOperations?.removeAll(keepCapacity: false)
        })
    }
    
}