[Swift 3] 해제 (Deinitialization)

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http://kka7.tistory.com/20

해제 (Deinitialization)

Swift 는 인스턴스가 더 이상 필요하지 않을 때

자동적으로 해제해주고 자원을 돌려준다.

ARC  로 인스턴스의 메모리를 관리한다.

일반적으로는 수동으로 수행할 필요가 없다.

하지만 리소스 작업할 때 몇 가지 추가적인 정리가 필요할 때가 있다. 

그 때 사용한다.

class Bank {

    static var coinsInBank = 10_000

    static func distribute(coins numberOfCoinsRequested: Int) -> Int {

        let numberOfCoinsToVend = min(numberOfCoinsRequested, coinsInBank)

        coinsInBank -= numberOfCoinsToVend

        return numberOfCoinsToVend

    }

    static func receive(coins: Int) {

        coinsInBank += coins

    }

}

class Player {

    var coinsInPurse: Int

    init(coins: Int) {

        coinsInPurse = Bank.distribute(coins: coins)

    }

    func win(coins: Int) {

        coinsInPurse += Bank.distribute(coins: coins)

    }

    deinit {

        Bank.receive(coins: coinsInPurse)

    }

}

var playerOne: Player? = Player(coins: 100)

print("A new player has joined the game with \(playerOne!.coinsInPurse) coins")

// Prints "A new player has joined the game with 100 coins"

print("There are now \(Bank.coinsInBank) coins left in the bank")

// Prints "There are now 9900 coins left in the bank"

playerOne!.win(coins: 2_000)

print("PlayerOne won 2000 coins & now has \(playerOne!.coinsInPurse) coins")

// Prints "PlayerOne won 2000 coins & now has 2100 coins"

print("The bank now only has \(Bank.coinsInBank) coins left")

// Prints "The bank now only has 7900 coins left"

playerOne = nil

print("PlayerOne has left the game")

// Prints "PlayerOne has left the game"

print("The bank now has \(Bank.coinsInBank) coins")

// Prints "The bank now has 10000 coins"