Multiple lists

Now that we have items created for one list, let's see how we can add multiple Shopping Lists to our app. It's quite similar to what we just did for Items, but before we get started, let's refactor our code so that it becomes easier to add a new Shopping List View Controller.

Refactoring to share code

Perform the following steps:

1. Create a new empty Swift file in our Controllers folder and call it BaseTableViewController.swift.
2. Inside of our BaseTableViewController.swift file, create a new class that inherits from the UITableViewController and has a requestInput method:

import UIKit 
class BaseTableViewController: UITableViewController {
  func requestInput(title: String, message: String, handler: 
      @escaping (String) -> ()) {
    let alert = UIAlertController(title: title,
                                  message: message,
                                  preferredStyle: .alert)

    alert.addTextField(configurationHandler: nil)

    alert.addAction(UIAlertAction(title...