OrdersViewController.swift

import UIKit

class OrdersViewController: UIViewController {
    // Create strong data source objects
    // Because tableView has a weak reference so it can be deallocated. 
    let orderDataSource = OrderDataSource()
    let completedOrdersDataSource = CompletedOrdersDataSource()
    
    public enum OrderTabs: Int {
        case current
        case completed
    }
    
    @IBOutlet weak var segmentedControl: UISegmentedControl!
    @IBOutlet weak var tableView: UITableView!
    
    override func viewDidLoad() {
        super.viewDidLoad()
        
        setupTableView()
    }
    
    func setupTableView() {
        tableView.dataSource = orderDataSource
    }
    
    @IBAction func segmentedControllerTapped(_ sender: UISegmentedControl) {
        if let tabs = OrderTabs(rawValue: sender.selectedSegmentIndex) {
            print("Selected tab: \(tabs)")
            switch tabs {
            case .current:
                tableView.dataSource = orderDataSource
            case .completed:
                tableView.dataSource = completedOrdersDataSource
            }
            tableView.reloadData()
        }
    }
}