import FDChessboardView
...
self.chessboard.dataSource = self

func chessboardView(board: FDChessboardView, pieceForSquare square: FDChessboardSquare) -> FDChessboardPiece? {
    return piecesByIndex[square.index] // you figure out which piece to show
}

/// The location of a square on a chess board
public struct FDChessboardSquare {

    /// From 0...7
    public var file: Int

    /// From 0...7
    public var rank: Int

    /// A format like a4
    public var algebriac: String { get }

    public var index: Int { get set }

    public init(index newIndex: Int)
}

/// The pieces on a chess board
public enum FDChessboardPiece : String {

    case WhitePawn

    case BlackPawn

    case WhiteKnight

    case BlackKnight

    case WhiteBishop

    case BlackBishop

    case WhiteRook

    case BlackRook

    case WhiteQueen

    case BlackQueen

    case WhiteKing

    case BlackKing
}

public protocol FDChessboardViewDataSource : class {

    /// What piece is on the square?
    public func chessboardView(board: FDChessboardView, pieceForSquare square: FDChessboardSquare) -> FDChessboardView.FDChessboardPiece?

    /// The last move
    public func chessboardViewLastMove(board: FDChessboardView) -> (from: FDChessboardView.FDChessboardSquare, to: FDChessboardView.FDChessboardSquare)?

    /// The premove
    public func chessboardViewPremove(board: FDChessboardView) -> (from: FDChessboardView.FDChessboardSquare, to: FDChessboardView.FDChessboardSquare)?
}

public protocol FDChessboardViewDelegate : class {

    /// Where can this piece move to?
    public func chessboardView(board: FDChessboardView, legalDestinationsForPieceAtSquare from: FDChessboardSquare) -> [FDChessboardView.FDChessboardSquare]

    /// Before a move happens (cannot be stopped)
    public func chessboardView(board: FDChessboardView, willMoveFrom from: FDChessboardSquare, to: FDChessboardSquare)

    /// After a move happened
    public func chessboardView(board: FDChessboardView, didMoveFrom from: FDChessboardSquare, to: FDChessboardSquare)

    /// Before a move happens (cannot be stopped)
    public func chessboardView(board: FDChessboardView, willMoveFrom from: FDChessboardSquare, to: FDChessboardSquare, withPromotion promotion: FDChessboardPiece)

    /// After a move happened
    public func chessboardView(board: FDChessboardView, didMoveFrom from: FDChessboardSquare, to: FDChessboardSquare, withPromotion promotion: FDChessboardPiece)
}

/// Display for a chess board
public class FDChessboardView : UIView {

    /// Color for "white" board squares
    public var lightBackgroundColor: UIColor

    /// Color for "black" board squares
    public var darkBackgroundColor: UIColor

    /// Color for where a piece is moving to
    public var targetBackgroundColor: UIColor

    /// Color for a legal square target
    public var legalBackgroundColor: UIColor

    /// Color for the last move square
    public var lastMoveColor: UIColor

    /// Color for a premove square
    public var premoveColor: UIColor

    /// Path for custom piece graphics
    public var pieceGraphicsDirectoryPath: String?

    /// Datasource to say which pieces are on each square
    public weak var dataSource: FDChessboardViewDataSource? { get set }

    /// Handler for user interaction with the view
    public weak var delegate: FDChessboardViewDelegate?

    /// Should piece moves be animated?
    public var doesAnimate: Bool

    /// Should legal squares be shown when a piece is selected?
    public var doesShowLegalSquares: Bool

    /// Should the lash move be shown?
    public var doesShowLastMove: Bool

    /// Should premove be shown?
    public var doesShowPremove: Bool

    /// UIView initializer
    public override init(frame: CGRect)

    /// UIView initializer
    required public init?(coder aDecoder: NSCoder)

    /// Add a piece onto the board
    public func setPiece(piece: FDChessboardPiece?, forSquare square: FDChessboardSquare)

    /// Repull all board information from data source
    public func reloadData()

    /// Move a piece on the board
    public func movePieceAtCoordinate(from: FDChessboardSquare, toCoordinate to: FDChessboardSquare) -> Bool

    /// Move a piece on the board
    public func movePieceAtCoordinate(from: FDChessboardSquare, toCoordinate to: FDChessboardSquare, andPromoteTo piece: FDChessboardPiece) -> Bool

    /// Premove a piece on the board
    public func premovePieceAtCoordinate(from: FDChessboardSquare, toCoordinate to: FDChessboardSquare) -> Bool

    /// Premove a piece on the board
    public func premovePieceAtCoordinate(from: FDChessboardSquare, toCoordinate to: FDChessboardSquare, andPromoteTo piece: FDChessboardPiece) -> Bool
}