Nested Functions Strong Reference Explanation

.swift

class Factory {
    
    var car: Car
    
    init(car: Car) {
        self.car = car
    }
    
    deinit {
        print("Factory model deallocated")
    }
    
}

class Car {
    
    var model: String
    
    init(model: String) {
        self.model = model
    }
    
    func showModel() {
        print("Model \(model)")
    }
    
    func startRunProccessWeakly() {
        
        weak var _self = self

        DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
            _self?.showModel()
        }
        
    }
    
    func startRunProccessStrongly() {
        
        DispatchQueue.main.asyncAfter(deadline: .now() + 3) {
            self.showModel()
        }
        
    }
    
    deinit {
        print("Car model deallocated")
    }
    
}

//First part with strong references
var factory: Factory? = Factory(car: Car(model: "Tesla"))
factory?.car.startRunProccessStrongly()
print("Factory try to deallocate")
factory = nil

//Second part with weak references
var factory: Factory? = Factory(car: Car(model: "Audi"))
factory?.car.startRunProccessWeakly()
print("Factory try to deallocate")
factory = nil