Swift Examples - Deinitialization

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The Swift Programming Language Examples

源码在 GitHub：https://github.com/gewill/The-Swift-Programming-Language-2.1-Examples

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// : Playground - noun: a place where people can play

import UIKit

//: 析构过程（Deinitialization）

//析构器只适用于类类型，当一个类的实例被释放之前，析构器会被立即调用。析构器用关键字deinit来标示，类似于构造器要用init来标示。

//有点像 UIViewController 的 func ViewWillDisappear

class Bank {
    static var coinsInBank = 10_000
    static func vendCoins(var numberOfCoinsToVend: Int) -> Int {
        numberOfCoinsToVend = min(numberOfCoinsToVend, coinsInBank)
        coinsInBank -= numberOfCoinsToVend
        return numberOfCoinsToVend
    }
    static func receiveCoins(coins: Int) {
        coinsInBank += coins
    }
}

class Player {
    var coinsInPurse: Int
    init(coins: Int) {
        coinsInPurse = Bank.vendCoins(coins)
    }
    func winCoins(coins: Int) {
        coinsInPurse += Bank.vendCoins(coins)
    }
    deinit {
        Bank.receiveCoins(coinsInPurse)
    }
}

var playerOne: Player? = Player(coins: 100)
print("A new player has joined the game with \(playerOne!.coinsInPurse) coins")
print("There are now \(Bank.coinsInBank) coins left in the bank")

playerOne?.winCoins(300)

print("The player has \(playerOne!.coinsInPurse) coins")
print("There are now \(Bank.coinsInBank) coins left in the bank")

playerOne = nil
print("The player has \(playerOne?.coinsInPurse) coins")
print("There are now \(Bank.coinsInBank) coins left in the bank")