let dataSource = BasicBlockDataSource<Example, BasicTableViewCell>() { (item: Example, cell: BasicTableViewCell, indexPath) -> Void in
    cell.titleLabel?.text = item.title
}

// Need to keep a strong reference to our data source.
self.dataSource = dataSource

// register the cell
tableView.ds_register(cellClass: BasicTableViewCell.self)
// bind the data source to the table view
tableView.ds_useDataSource(dataSource)

dataSource.items =  <<retrieve items>> // Can be set and altered at anytime

let dataSource = BasicBlockDataSource<Example, BasicCollectionViewCell>() { (item: Example, cell: BasicCollectionViewCell, indexPath) -> Void in
    cell.titleLabel?.text = item.title
}

// Need to keep a strong reference to our data source.
self.dataSource = dataSource

// register the cell
collectionView.ds_register(cellClass: BasicCollectionViewCell.self)
// bind the data source to the collection view
collectionView.ds_useDataSource(dataSource)

dataSource.items =  <<retrieve items>> // Can be set and altered at anytime

class AppStoreFeaturedSectionTableViewCell: UITableViewCell { ... }
class AppStoreQuickLinkLabelTableViewCell: UITableViewCell { ... }
class AppStoreQuickLinkTableViewCell: UITableViewCell { ... }
class AppStoreFooterTableViewCell: UITableViewCell { ... }
class AppStoreLoadingTableViewCell: UITableViewCell { ... }

class AppStoreLoadingDataSource: BasicDataSource<Void, AppStoreLoadingTableViewCell> {
    // loading should take full screen size.
    override func ds_collectionView(_ collectionView: GeneralCollectionView, sizeForItemAt indexPath: IndexPath) -> CGSize {
        return collectionView.size
    }
}
class AppStoreFooterDataSource: BasicDataSource<Void, AppStoreFooterTableViewCell> { ... }
class AppStoreQuickLinkDataSource: BasicDataSource<FeaturedQuickLink, AppStoreQuickLinkTableViewCell> { ...  }
class AppStoreFeaturedAppsDataSource: BasicDataSource<FeaturedApp, AppStoreFeaturedAppCollectionViewCell> { ... }
class AppStoreFeaturedAppsSectionDataSource: BasicDataSource<FeaturedSection, AppStoreFeaturedSectionTableViewCell> { ... }
class AppStoreQuickLinkLabelDataSource: BasicDataSource<String, AppStoreQuickLinkLabelTableViewCell> { ... }

class AppStoreFeaturedPageDataSource: CompositeDataSource {
    init() { super.init(sectionType: .single)] }

    var page: FeaturedPage? {
        didSet {
            // remove all existing data sources
            removeAllDataSources()

            guard let page = page else {
                return
            }

            // add featured apps
            let featuredApps = AppStoreFeaturedAppsSectionDataSource()
            featuredApps.setSelectionHandler(UnselectableSelectionHandler())
            featuredApps.items = page.sections
            add(featuredApps)

            // add quick link label
            let quickLinkLabel = AppStoreQuickLinkLabelDataSource()
            quickLinkLabel.setSelectionHandler(UnselectableSelectionHandler())
            quickLinkLabel.items = [page.quickLinkLabel]
            add(quickLinkLabel)

            // add quick links
            let quickLinks = AppStoreQuickLinkDataSource()
            quickLinks.items = page.quickLinks
            add(quickLinks)

            // add footer
            let footer = AppStoreFooterDataSource()
            footer.setSelectionHandler(UnselectableSelectionHandler())
            footer.items = [Void()] // we add 1 element to show the footer, 2 elements will show it twice. 0 will not show it.
            add(footer)
        }
    }
}

class AppStoreDataSource: SegmentedDataSource {

    let loading = AppStoreLoadingDataSource()
    let page = AppStoreFeaturedPageDataSource()

    // reload data on index change
    override var selectedDataSourceIndex: Int {
        didSet {
            ds_reusableViewDelegate?.ds_reloadData()
        }
    }

    override init() {
        super.init()
        loading.items = [Void()] // we add 1 element to show the loading, 2 elements will show it twice. 0 will not show it.

        add(loading)
        add(page)
    }
}

tableView.ds_register(cellNib: AppStoreFeaturedSectionTableViewCell.self)
tableView.ds_register(cellNib: AppStoreQuickLinkLabelTableViewCell.self)
tableView.ds_register(cellNib: AppStoreQuickLinkTableViewCell.self)
tableView.ds_register(cellNib: AppStoreFooterTableViewCell.self)
tableView.ds_register(cellNib: AppStoreLoadingTableViewCell.self)

tableView.ds_useDataSource(dataSource)

  // show loading indicator
  dataSource.selectedDataSourceIndex = 0

  // get the data from the service
  service.getFeaturedPage { [weak self] page in

    // update the data source model
    self?.dataSource.page.page = page

    // show the page
    self?.dataSource.selectedDataSourceIndex = 1
}