Memory Management Code Review

At Glassdoor, you're reviewing a feed screen before it merges. The reviewer's note is short: "had you look over some code and describe what needed to be fixed regarding memory management and weak self, then fix it."

class FeedViewController: UIViewController {

    var apiClient: APIClient
    var items: [FeedItem] = []
    var notificationToken: NSObjectProtocol?

    init(apiClient: APIClient) {
        self.apiClient = apiClient
        super.init(nibName: nil, bundle: nil)
    }

    required init?(coder: NSCoder) { fatalError() }

    override func viewDidLoad() {
        super.viewDidLoad()
        loadFeed()
        notificationToken = NotificationCenter.default.addObserver(forName: .feedDidUpdate, object: nil, queue: .main) { _ in
            self.loadFeed()
        }
    }

    func loadFeed() {
        apiClient.fetchFeed { result in
            switch result {
            case .success(let items):
                self.items = items
                self.reloadTable()
            case .failure(let error):
                self.showError(error)
            }
        }
    }

    func refreshOnTimer() {
        Timer.scheduledTimer(withTimeInterval: 30, repeats: true) { _ in
            self.loadFeed()
        }
    }

    func reloadTable() { }
    func showError(_ error: Error) { }
}

Describe what needs to be fixed here regarding memory management and weak self, then explain exactly how you'd fix it. This is answered as free text, so explain the change and why, rather than submitting an edited file.