Tic tac toe finding win? - swift

Question

I am making a tic tac toe game in Swift for 2 players. Now I know I can find a winner by making outlets for the 9 buttons and then writing for all the 3 in row cases, but I was wondering if there is a better way to do this? And is there a better way to write my switch statement?
#IBOutlet weak var button1: UIButton!
#IBOutlet weak var button2: UIButton!
#IBOutlet weak var button3: UIButton!
#IBOutlet weak var button4: UIButton!
#IBOutlet weak var button5: UIButton!
#IBOutlet weak var button6: UIButton!
#IBOutlet weak var button7: UIButton!
#IBOutlet weak var button8: UIButton!
#IBOutlet weak var button9: UIButton!
var player = 1
#IBAction func playersTurn(sender: UIButton){
switch player{
case 1: sender.setTitle("X", forState: UIControlState.Normal); player = 2;break;
case 2: sender.setTitle("O", forState: UIControlState.Normal); player = 1;break;
default:exit(0); break
}
}

Answer 1

I would set the tag property on your buttons using values 0-9 in order from top to bottom, left to right, like so:
[ 0 ][ 1 ][ 2 ]
[ 3 ][ 4 ][ 5 ]
[ 6 ][ 7 ][ 8 ]
Then create a model to represent each square and give it a corresponding index value, as well as a reference to the player who owns it. Then you can handle you game logic with those models and update the UI by getting references to your buttons with viewForTag(_:). Here's my version:
class Square {
var owningPlayer: Player?
let index: Int
init( index: Int ) {
self.index = index
}
}
class Player {
let symbol: String
init( symbol: String ) {
self.symbol = symbol
}
}
class ViewController: UIViewController {
var squares = [Square]()
var players = [Player]()
var currentPlayer: Player?
override func viewDidLoad() {
super.viewDidLoad()
self.players = [ Player(symbol: "X"), Player(symbol: "O") ]
self.currentPlayer = self.players[0]
// Create squares
for i in 0..<9 {
self.squares.append( Square(index: i) )
}
}
#IBAction func buttonPressed( button: UIButton ) {
guard let player = self.currentPlayer else {
fatalError( "Don't have a current player!" )
}
if let square = self.squares.filter({ $0.index == button.tag }).first {
// Update model
square.owningPlayer = player
// Update UI
button.setTitle( player.symbol, forState: .Normal )
}
if self.checkWin() {
print( "\(player.symbol) wins!" )
}
else {
self.currentPlayer = self.players.filter({ $0 !== player }).first
}
}
func checkWin() -> Bool {
guard let player = self.currentPlayer else {
fatalError( "Don't have a current player!" )
}
let winningSequences = [
// Horizontal rows
[ 0, 1, 2 ],
[ 3, 4, 5 ],
[ 6, 7, 8 ],
// Diagonals
[ 0, 4, 8 ],
[ 2, 4, 6 ],
// Vertical rows
[ 0, 3, 6 ],
[ 1, 4, 7 ],
[ 2, 5, 8 ],
]
// Get indexes owned by this player
let selectedIndexes = self.squares.filter({ $0.owningPlayer === player }).map { $0.index }
// Change the sequence arrays into sets for accurate comparison using `contains(_:)`
if winningSequences.map({ Set<Int>($0) }).contains( Set<Int>(selectedIndexes) ) {
return true
}
return false
}
}

Answer 2

Although #Patrick Lynch's answer is excellent I found that it didn't match a win should the game go beyond 3 moves.
This is because he is only checking if any of the winningSequences contains a current move sequence (selectedIndexes). As the winningSequences map only has a max of 3 items it'll never contain a set of 4 moves.
To resolve this I changed contains to subset. i.e is a winningSequence (0, 1, 2) a subset of the selectedIndexes (0, 5, 1, 2)
Replace
if winningSequences.map({ Set<Int>($0) }).contains( Set<Int>(selectedIndexes) ) {
return true
}
with
for seq in winningSequences.map( { Set<Int>($0)}) {
if seq.isSubset(of: selectedIndexes) {
return true
}
}
I'm still new to swift so if I'm wrong or anyone has a better idea then I'd be happy to hear it.