Inspired by Andy Matuschak, https://gist.github.com/andymatuschak/f1e1691fa1a327468f8e

TableViewDataSource.swift

public protocol TableViewCellFactoryType {

    typealias DataItem
    typealias Cell: UITableViewCell

    func cellForItem(item: DataItem, inTableView tableView: UITableView, atIndexPath indexPath: NSIndexPath) -> Cell

    func configureCell(cell: Cell, forItem item: DataItem, inTableView tableView: UITableView, atIndexPath indexPath: NSIndexPath) -> Cell

}


public struct TableViewCellFactory<Cell: UITableViewCell, DataItem>: TableViewCellFactoryType {

    typealias CellConfigurationClosure = (Cell, DataItem, UITableView, NSIndexPath) -> Cell

    private let reuseIdentifier: String
    private let cellConfigurator: CellConfigurationClosure

    public init(reuseIdentifier: String, cellConfigurator: CellConfigurationClosure) {
        self.reuseIdentifier = reuseIdentifier
        self.cellConfigurator = cellConfigurator
    }

    public func cellForItem(item: DataItem, inTableView tableView: UITableView, atIndexPath indexPath: NSIndexPath) -> Cell {
        let cell = tableView.dequeueReusableCellWithIdentifier(reuseIdentifier, forIndexPath: indexPath) as Cell
        return configureCell(cell, forItem: item, inTableView: tableView, atIndexPath: indexPath)
    }

    public func configureCell(cell: Cell, forItem item: DataItem, inTableView tableView: UITableView, atIndexPath indexPath: NSIndexPath) -> Cell {
        return self.cellConfigurator(cell, item, tableView, indexPath)
    }

}


public class TableViewDataSource <SectionCollection: CollectionType, CellFactory: TableViewCellFactoryType, DataItem
                                    where
                                    SectionCollection.Index == Int,
                                    SectionCollection.Generator.Element: CollectionType,
                                    SectionCollection.Generator.Element.Generator.Element == DataItem,
                                    SectionCollection.Generator.Element.Index == Int,
                                    CellFactory.DataItem == DataItem>: NSObject, UITableViewDataSource {

    public var sections: SectionCollection

    public let cellFactory: CellFactory

    public init(sections: SectionCollection, cellFactory: CellFactory) {
        self.sections = sections
        self.cellFactory = cellFactory
    }

    // MARK: table view data source

    public func numberOfSectionsInTableView(tableView: UITableView) -> Int {
        return countElements(sections)
    }

    public func tableView(tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
        return countElements(sections[section])
    }

    public func tableView(tableView: UITableView, cellForRowAtIndexPath indexPath: NSIndexPath) -> UITableViewCell {
        return cellFactory.cellForItem(sections[indexPath.section][indexPath.row], inTableView: tableView, atIndexPath: indexPath)
    }

}

Unfortunately this doesn't compile. 😢

If TableViewDataSource does not inherit from NSObject and does not conform to UITableViewDataSource, then this compiles successfully.

Thus, it looks like the only solution is to have a "proxy/bridgeDataSource" object as seen here:
https://gist.github.com/andymatuschak/f1e1691fa1a327468f8e