Swift Method: deinit is not invoked

Question

Here is a code example from Swift Programming Book by Apple (in chapter: Deinitializers)

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

class MyPlayer {
    var coinsInPurse: Int
    init(coins: Int){
        coinsInPurse = Bank.vendCoins(coins)
    }
    func winCoins(coins: Int){
        coinsInPurse += Bank.vendCoins(coins)
    }
    deinit {
        Bank.receiveCoins(coinsInPurse)
        println("Bank has \(Bank.coinsInBank) coins")
    }
}

var playerOne: MyPlayer? = MyPlayer(coins: 250)
playerOne?.winCoins(100)
println("PlayerOne has \(playerOne!.coinsInPurse) coins")
println("Bank has \(Bank.coinsInBank) coins")
playerOne = nil
println("Bank has \(Bank.coinsInBank) coins")  //This prints 9650
                                               //instead of 10000

It appears the deinit method is not being invoked. Why?

This is normal in case you are using playground as Memory management work bit different there. Have you tried in compiled app? — Kirsteins, Mar 24 '15 at 13:28
Right @Kirsteins, it works correctly in compiled app but not in playground. — Tushar, Mar 25 '15 at 05:53

score 1 · Accepted Answer · answered Mar 24 '15 at 14:28

If you are trying this in an Xcode 6.1 (and possibly 6.2, I don't have it installed) playground, you'll see this behavior because playgrounds sometimes do extra retains you weren't aware of. If you paste this code into a scratch Swift console application in 6.1.1 it works correctly and prints 10000.

In the latest Xcode beta (6.3) this code works as expected even in a playground.

Swift Method: deinit is not invoked

1 Answers1