A way to observe .willEnterForegroundNotification and .didEnterBackgroundNotification with no potential memory issues

ForegroundBackgroundObservable.swift

import UIKit

public protocol EnterForegroundObservable: AnyObject {
    var applicationWillEnterForegroundObservation: Any? { get set }
    typealias ForegroundBackgroundObservationCompletionHandler = () -> Void
    func applicationWillEnterForegroundObservation(completion: ForegroundBackgroundObservationCompletionHandler?)
}

public extension EnterForegroundObservable {
    func applicationWillEnterForegroundObservation(completion: ForegroundBackgroundObservationCompletionHandler?) {
        applicationWillEnterForegroundObservation = NotificationCenter.default.addObserver(
        forName: UIApplication.willEnterForegroundNotification, object: nil, queue: nil) { _ in
            completion?()
        }
    }
}

public protocol EnterBackgroundObservable: AnyObject {
    var applicationDidEnterBackgroundObservation: Any? { get set }
    typealias ForegroundBackgroundObservationCompletionHandler = () -> Void
    func applicationDidEnterBackgroundObservation(completion: ForegroundBackgroundObservationCompletionHandler?)
}

public extension EnterBackgroundObservable {
    func applicationDidEnterBackgroundObservation(completion: ForegroundBackgroundObservationCompletionHandler?) {
        applicationDidEnterBackgroundObservation = NotificationCenter.default.addObserver(
        forName: UIApplication.didEnterBackgroundNotification, object: nil, queue: nil) { _ in
            completion?()
        }
    }
}