let collectionView = UICollectionView() // or UITableView()
struct FeaturedModel {}

// 1. Cells
class FeaturedTopCell: UICollectionViewCell {}
class QuickLinksCell: UICollectionViewCell {}
class ActionBlueCell: UICollectionViewCell {}
class ActionRoundedRectCell: UICollectionViewCell {}

// 2. Basic Data Sources
class FeaturedTopDataSource: BasicDataSource<FeaturedModel, FeaturedTopCell> { }
class QuickLinksDataSource: BasicDataSource<String, QuickLinksCell> { }
class ActionBlueDataSource: BasicDataSource<String, ActionBlueCell> { }
class ActionRoundedRectDataSource: BasicDataSource<String, ActionRoundedRectCell> { }

// 3. Create data source instances once.
let featuredDS = FeaturedTopDataSource(reuseIdentifier: "cellReuse1")
let quickLinksDS = QuickLinksDataSource(reuseIdentifier: "cellReuse2")
let actionBlueDS = ActionBlueDataSource(reuseIdentifier: "cellReuse3")
let actionRoundedRectDS = ActionRoundedRectDataSource(reuseIdentifier: "cellReuse4")

// 4. Create first section hierarchy.
let firstSection = CompositeDataSource(sectionType: .single)
firstSection.add(featuredDS)
firstSection.add(quickLinksDS)
firstSection.add(actionBlueDS)

// 5. Complete the hierarchy.
let outerDS = CompositeDataSource(sectionType: .multi)
outerDS.add(firstSection)
outerDS.add(actionRoundedRectDS)

// 6. set data sources to the collection view.
collectionView.ds_useDataSource(outerDS)

// 7. You can set the data/items later or earlier or at any point of time.
// For example wait until a web service returns its data.
featuredDS.items = [FeaturedModel()]
quickLinksDS.items = ["Quick Links"]
actionBlueDS.items = ["Add Payment Method", "New to the App Store", "About in-App Purchases", "Parents' Guide to iTunes", "App Collections"]
actionRoundedRectDS.items = ["Redeem", "Send Gifts"]

// 8. We can reload the collection view if the data is loaded async.
collectionView.reloadData()

let dataSource = BasicBlockDataSource<Example, UITableViewCell>(reuseIdentifier: "cell") { (item: Example, cell: UITableViewCell, _) -> Void in
    cell.textLabel?.text = item.title
    cell.contentView.backgroundColor = nil
}

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

tableView.ds_useDataSource(dataSource)
dataSource.items =  /* <<retrieve items>> Can be called later no need to set them immediately. */Service.getExamples()

// optionally adding a selection handler
let selectionHandler = BlockSelectionHandler<Example, UITableViewCell>()
selectionHandler.didSelectBlock = { [weak self] dataSource, _, indexPath in
    let item = dataSource.item(at: indexPath)
    self?.performSegue(withIdentifier: item.segue, sender: self)
}
dataSource.setSelectionHandler(selectionHandler)

// We can use BasicDataSource by subclassing it or use BasicBlockDataSource as in the previous example.
class ColorsDataSource: BasicDataSource<Color, UITableViewCell> {

    override func ds_collectionView(_ collectionView: GeneralCollectionView, configure cell: UITableViewCell, with item: Color, at indexPath: IndexPath) {
        cell.backgroundColor = item.color
    }
}

class ContactsDataSource: BasicDataSource<Contact, ContactCell> {

    override func ds_collectionView(_ collectionView: GeneralCollectionView, configure cell: ContactCell, with item: Contact, at indexPath: IndexPath) {
        cell.configure(forContact: item)
    }
}

extension ContactCell {
    func configure(forContact contact: Contact) {
        textLabel?.text = contact.name
        detailTextLabel?.text = contact.email
    }
}

// ....
// Then in the view controller.
class ViewController: UITableViewController {
    var dataSource: CompositeDataSource!
    override func viewDidLoad() {
        super.viewDidLoad()

        let dataSource = CompositeDataSource(sectionType: .single)
        // strong refernce
        self.dataSource = dataSource
        let colorsDataSource = ColorsDataSource(reuseIdentifier: "color")
        let contactsDataSource = ContactsDataSource(reuseIdentifier: "contact")

        // add the data sources
        dataSource.add(contactsDataSource)
        dataSource.add(colorsDataSource)

        tableView.ds_useDataSource(dataSource)

        // optionally selection handler
        colorsDataSource.setSelectionHandler(AlertNameSelectionHandler<Color, UITableViewCell>(typeName: "color"))
        contactsDataSource.setSelectionHandler(AlertNameSelectionHandler(typeName: "contact"))

        // specify different heights
        colorsDataSource.itemHeight = 30
        contactsDataSource.itemHeight = 50

        colorsDataSource.items = /* << Retrieve Colors >> */ []
        contactsDataSource.items = /* << Retrieve Contacts >> */ []
    }
}

// FOR COMPLETENESS: we added the non-essential classes below.
class ContactCell: UITableViewCell { }

struct Contact: NameableEntity {
    let name: String
    let email: String
}

struct Color: NameableEntity {
    let color: UIColor
    let name: String
}

protocol NameableEntity {
    var name: String { get }
}

class AlertNameSelectionHandler<ItemType: NameableEntity, CellType: ReusableCell>: DataSourceSelectionHandler {

    let typeName: String
    init(typeName: String) {
        self.typeName = typeName
    }

    func dataSource(
        _ dataSource: BasicDataSource<ItemType, CellType>,
        collectionView: GeneralCollectionView,
        didSelectItemAt indexPath: IndexPath) {
        UIAlertView(title: "", message: dataSource.item(at: indexPath).name + " " + typeName + " tapped!", delegate: nil, cancelButtonTitle: "Ok").show()
    }
}