ios – NSDiffableDataSource – the cellProvider on my CollectionView Information Supply isn’t being known as?

I’ve a knowledge supply like so

   fileprivate func makeRecordsDataSource() -> RecordsDataSource {
        let dataSource = RecordsDataSource(
            collectionView: recordsCollectionView,
            cellProvider: { (collectionView, indexPath, recordItem) ->
              UICollectionViewCell? in
                change recordItem.kind {
                case .Rep:
                    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: RepRecordCell.identifier, for: indexPath) as? RepRecordCell
                    cell!.configure(with: recordItem)
                    return cell
                case .Picture:
                    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: ImageRecordCell.identifier, for: indexPath) as? ImageRecordCell
                    cell!.configure(with: recordItem)
                    return cell
                case .Video:
                    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: VideoRecordCell.identifier, for: indexPath) as? VideoRecordCell
                    cell!.configure(with: recordItem)
                    return cell
                case .Textual content:
                    let cell = collectionView.dequeueReusableCell(withReuseIdentifier: TextRecordCell.identifier, for: indexPath) as? TextRecordCell
                    cell!.configure(with: recordItem)
                    return cell
                }
            })
        return dataSource
    }

For my part controller I’ve

non-public lazy var recordsDataSource = makeRecordsDataSource()

Then a perform to use a snapshot to my knowledge supply….

func applyRecordsSnapshot(days:[YearMonthDay]) {
    var snapshot = RecordsDataSourceSnapshot()
    snapshot.appendSections(days)
    var i = 0
    for ymd in days {
        sectionMap[ymd] = i
        snapshot.appendItems(ymd.recordItems,toSection: ymd)
        i += 1
    }
    recordsDataSource.apply(snapshot, animatingDifferences: false)
}

within the debugger, once I have a look at the snapshot.numberOfItems, I see 4, so there are 4 sections… However for some cause the closure cellProvider by no means will get known as once I put breakpoints within it. Would not it get known as as soon as for every cell within the snapshot?