Adding a Shopping List Item

If you have successfully implemented the create and delete functionality for an item in the Shopping List, then good job! If not, we will walk through how you can do so. It is very similar to how we implemented it on the Shopping List. To implement the functionality for adding items to a Shopping List, we need to follow these steps:

1. Open the Item.swift file inside the iOS project and add a new instance variable to store the shoppingListId. This variable will be passed to the API server along with the name and the isChecked state of the item when creating it so that it can associate this item with the shopping list it is being added to:

var shoppingListId: String?

2. Add the data commuted property, similar to the one we added in the ShoppingList class, which will convert our object into JSON data that will be passed to our API server. In this case, we will use JSONEncoder instead of JSONSerializer. The reason why we did not convert ShoppingList to JSON data using this...