class Bank { //类型属性 static var coinsInBank = 10_000 //类型方法 static func distribute(coins numberOfCoinsRequested: Int) -> Int { let numberOfCoinsToVend = min(numberOfCoinsRequested, coinsInBank) coinsInBank -= numberOfCoinsToVend return numberOfCoinsToVend } //类型方法 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) } }
override func viewDidLoad() { super.viewDidLoad() // Do any additional setup after loading the view, typically from a nib. //Deinitialization //关键字 deinit, 只有 Class 有 deinit, 在 dealloc 前调用 //Swift 使用 ARC 自动管理内存 //需要在 deinit 中手动处理的: 文件关闭, 对象销毁, KVO移除, 通知移除, NSTimer销毁 //每个 Class 只能有一个 deinit, 没有参数 //不能主动调用, 子类继承父类的 deinit 函数, 父类 deinit 函数在子类 deinit 函数调用结束后调用, 父类deinit 函数总是会被调用,即使子类的没有调用 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!.win(coins: 2_000) print("PlayerOne won 2000 coins & now has \(playerOne!.coinsInPurse) coins") print("The bank now only has \(Bank.coinsInBank) coins left") //对象置为 nil 就会调用 Player 类中的 deinit 方法 playerOne = nil print("PlayerOne has left the game") print("The bank now has \(Bank.coinsInBank) coins") }
deinit { print("~~~~~~~~") }