Learning Swift™ Programming

Taking Sides

You’re almost done creating an AI in Swift. If the computer player can’t seize a victory, block the opponent’s win, or take a center tile, it has only two options. It tries step 4, claiming a corner tile. If all corners are taken, it falls back to its last resort, marking a middle tile. Steps 4 and 5 are similar in terms of logic:

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    func firstAvailable(#isCorner:Bool) -> Int? {        var spots = isCorner ? [0,2,6,8] : [1,3,5,7]        for spot in spots {            println("checking \(spot)")            if !isOccupied(spot) {                println("not occupied \(spot)")                return spot            }        }        return nil    }

The firstAvailable method loops through an array of tile ...