Gist to avoid Strong Reference Cycles when using closures

WeakClosures.playground

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

import UIKit

class LoginView {
    
    var loginSuccessCallback: ((Int)->Void)?
    
    init() {
        println("login: - hello")
    }
    
    func login() {
        println("loging in")
        loginSuccessCallback?(2)
    }
    
    deinit {
        println("login: - goodbye")
    }
}

class Controller {
    var login: LoginView?
    
    init() {
        login = LoginView()
        
        //Toggle the following lines' comments and you will notice the "login: - goodbye" won't be print
        // login?.loginSuccessCallback = loginCallback
        login?.loginSuccessCallback = { [unowned self] anInt in
            self.loginCallback(anInt)
        }
    }
    
    func requestLogin() {
        login!.login()
    }
    
    func loginCallback(anInt: Int) {
        println("yay logged in")
    }
}

var c: Controller? = Controller()
c!.requestLogin()
c = nil