My solution to Swift Ninja Final Challenge

gistfile1.swift

enum Suit {
    case Clubs, Diamonds, Hearts, Spades
}

enum Rank {
    case Jack, Queen, King, Ace
    case Num(Int)
}

struct Card {
    let suit: Suit
    let rank: Rank
}

func countHand(cards: [Card], calc: ((Card, Card) -> Int)? = nil) -> Int
{
    return
        !calc ?
        // No calc closure defined (first call to countHand). Create closure and recall countHand with it!
        countHand(cards, { (c1:Card, c2:Card) -> Int in
            switch (c1.rank, c2.rank, c1.suit, c2.suit) {
            case (_, Rank.Num(let internalRank),Suit.Hearts,  _) where internalRank % 2 == 1:
                return 2 * internalRank
            case (Rank.Num(5), Rank.Ace, Suit.Diamonds, _):
                return 100
            default:
                return 0
            }}) :
        // Calc closure defined. Just call calc + recursive countHand with cards array without first card
        (cards.count < 2 ?
            0 :
            calc!(cards[0], cards[1]) + countHand(Array<Card>(dropFirst(cards)), calc: calc))
}