Dangling Pointer Playground (weak, unowned)

ClosuresClosuresClosures

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

import UIKit

class Test {
    
    let handler: () -> ()
    
    deinit {
        print("dealloc'd")
    }
    
    init(withHandler handler: () -> ()) {
        self.handler = handler
    }
    
    func something() {
        handler()
        
        print("before")
        dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_DEFAULT, 0)) { [unowned self] in
            print("\(unsafeAddressOf(self)) wwdsfdsfdsfd")
            self.somethingElse()
        }
        print("after")
    }
    
    func somethingElse() {
        print("\(unsafeAddressOf(self)) Hmm")
    }
    
}

class SomewhereElse {
    var t: Test?
    
    func test() {
        t = Test(withHandler: { () -> () in
            print(unsafeAddressOf(self.t!))
            self.t = nil
            
        })
        
        t!.something()
    }
}

let s = SomewhereElse()

s.test()
print("done")