Article_008 https://nalexn.github.io/separation-of-concerns/

Article_008_SoC_02.swift

protocol ListRepository {
    func loadList(completion: @escaping ([Item], Error?) -> Void)
}

Article_008_SoC_03.swift

class ListViewController: UIViewController {
    
    var items: [Item] = []
    var tableView: UITableView?
    var repository: ListRepository
    
    override func viewDidLoad() {
        repository.loadList { [weak self] (list, error) in
            self?.items = list
            self?.tableView?.reloadData()
        }
    }
}