strong delegate causing strong reference cycle (even with `struct`); making it `weak` solves this

gistfile1.txt

// this is strong reference cycle

protocol MyStructDelegate {
    func didSomethingHappen()
}

struct MyStruct {
    var delegate: MyStructDelegate
    
    init(delegate: MyStructDelegate) {
        self.delegate = delegate
    }
}

class SecondViewController: UIViewController, MyStructDelegate {

    var myStruct: MyStruct!
    
    override func viewDidLoad() {
        super.viewDidLoad()

        myStruct = MyStruct(delegate: self)
    }
    
    func didSomethingHappen() {
        println(__FUNCTION__)
    }
    
    deinit {
        println("Never get here")
    }

}

// this is not strong reference cycle

protocol MyStructDelegate : class {
    func didSomethingHappen()
}

struct MyStruct {
    unowned var delegate: MyStructDelegate
    
    init(delegate: MyStructDelegate) {
        self.delegate = delegate
    }
}

class SecondViewController: UIViewController, MyStructDelegate {

    var myStruct: MyStruct!
    
    override func viewDidLoad() {
        super.viewDidLoad()

        myStruct = MyStruct(delegate: self)
    }
    
    func didSomethingHappen() {
        println(__FUNCTION__)
    }
    
    deinit {
        println("Got here")
    }

}

Good Example

really good example to explain it clearly and simply, thanks

Very helpful. Thank you