card-game.swift

import Darwin

extension Array {
    mutating func shuffle() -> Array {
        // this will sometimes crash (submitted bug #17127524)
        self.sort { _,_ in arc4random_uniform(2) == 1 }
        return self
    }
    mutating func removeAtIndexes( i:Int... ) {
        var indexes = i
        indexes.sort(>)
        for i in indexes { removeAtIndex(i) }
    }
}

class CardSet {
    struct Card {
        enum Suit:Int {
            case Hearts, Diamonds, Clubs, Spades
        }
        enum Rank:Int {
            case Two, Three, Four, Five, Six
            case Seven, Eight, Nine, Ten
            case Jack, Queen, King, Ace
        }
        
        let suit:Suit
        let rank:Rank
    }
    
    var cards:[Card]
    
    init() { cards = [] }
    init( _ cards:[Card] ) { self.cards = cards }
    
    var isEmpty:Bool { return cards.isEmpty }
}

class Deck:CardSet {
    override init() {
        var array = Array(0...52)
        let indexes = array.shuffle()
        super.init(indexes.map { index in
            let suit = Card.Suit(rawValue: index % 4)!
            let rank = Card.Rank(rawValue: index % 13)!
            return Card(suit: suit, rank: rank)
            })
    }
    
    func drawCard() -> Card { return cards.removeLast() }
}

class Hand:CardSet {
    var canPlay:Bool {
        return cards.count >= 4 && (ranksMatch() || suitsMatch())
    }
    
    func play() {
        if ranksMatch() { cards.removeAtIndexes(3, 2, 1, 0) }
        else if suitsMatch() { cards.removeAtIndexes(2, 1) }
    }
    
    func add( card:Card ) { cards.insert(card, atIndex: 0) }
    
    func ranksMatch() -> Bool { return cards[0].rank == cards[3].rank }
    func suitsMatch() -> Bool { return cards[1].suit == cards[2].suit }
}

struct Game {
    var deck = Deck()
    var hand = Hand()
    
    func play() -> Bool {
        while !deck.isEmpty {
            hand.add( deck.drawCard() )
            while hand.canPlay { hand.play() }
        }
        return hand.isEmpty
    }
}

let games = 1000
var wins = 0
for _ in 0...games { if Game().play() { wins++ } }

let winningPercentage = Double(wins) / Double(games)
println("Played \(games) games, \(wins) (\(winningPercentage)%) wins.")

Xcode 6.2 compliant, I think?
Not sure what it is supposed to do but fixed the syntax changes.