Capture ro'yxatida doimo weak yoki unowned ishlatish…

Ha, har doim emas.

Weak va unowned, closure'larda kuchli referens tsikllarini (retention cycles) oldini olish uchun ishlatiladi, agar closure ob'ektga kuchli referens tutsa va ob'ekt ham o'z navbatida closure'ga kuchli referens tutsa.

weak yoki unowned ishlatish zarur bo'lsa, closure self yoki boshqa referens turiga kuchli referens oladi va kuchli referens tsikli yuzaga kelishi mumkin.

weak/unowned ishlatmaslik kerak bo'lgan holatlar:

Closure qiymat turlarini (strukturalar, enumlar, tuple'lar) tutib oladi. Ular tutib olinish paytida nusxa olinadi va kuchli referens tsikllar yuzaga kelmaydi.
Closure referens turini tutib olsa-da, ikkilamchi kuchli referens tsikli mavjud emas. Masalan, agar closure lokal ravishda metod ichida yaratilgan bo'lsa va ob'ektga saqlanmasa.
Closure qisqa muddatli bo'lib, u ob'ektdan avval bajariladi. Masalan, Completion Handler sifatida uzatilgan va darhol bajariladigan closure.

weak va unowned orasidagi tanlov:

weak: ob'ekt har doim nil bo'lishi mumkin, closure bajarilishidan oldin. Referens ObjectType? sifatida e'lon qilinadi. nil tekshiruvi qilish kerak.
unowned: ob'ekt har doim mavjud bo'ladi, deb bilinsa, referens ObjectType sifatida. nil tekshiruvi qilish shart emas. unowned bilan nil bo'lgan ob'ekt ishlatilsa, xatolik yuz beradi.

// `weak`/`unowned` kerak emas (qiymat turini tutib oladi)
struct MyStruct {
    var value: Int
}

let myStruct = MyStruct(value: 10)
let closure = {
    print(myStruct.value) // myStruct nusxasini tutadi
}
closure()

// `weak`/`unowned` kerak emas (lokal closure)
class MyClass {
    func doSomething() {
        let localValue = 5
        let localClosure = {
            print(self.description) // self tutib oladi, lekin closure MyClassda saqlanmaydi
        }
        localClosure()
    }

    var description: String {
        return "Instance of MyClass"
    }
}

let myObject = MyClass()
myObject.doSomething()

// `weak` kerak (potensial `nil`)
class AsyncOperation {
    var completionHandler: (() -> Void)?

    func performOperation() {
        // Asinxron ishni simulyatsiya qilish
        DispatchQueue.global().async {
            print("Operation completed")
            self.completionHandler?() // optional chaining
        }
    }

    deinit {
        print("AsyncOperation deinitialized")
    }
}

class ViewController {
    var op: AsyncOperation?

    func setupOperation() {
        op = AsyncOperation()
        op?.completionHandler = { [weak self] in // weak self
            guard let self = self else { return }
            print("Completion handler in ViewController: \(self)")
        }
    }

    deinit {
        print("ViewController deinitialized")
    }
}

// `unowned` kerak (garantli mavjud)
class Button {
    var action: (() -> Void)?

    func tap() {
        action?()
    }

    deinit {
        print("Button deinitialized")
    }
}

class ViewControllerWithButton {
    var button: Button

    init() {
        button = Button()
        button.action = { [unowned self] in // unowned self
            print("Button tapped in ViewControllerWithButton: \(self)")
        }
    }

    deinit {
        print("ViewControllerWithButton deinitialized")
    }
}

Capture ro'yxatida doimo weak yoki unowned ishlatish kerakmi?