Subclassing an Objective-C Class
In this section, you are going to create a new class named BNRItem. BNRItem will be a subclass of NSObject.
Figure 2.9 Class hierarchy including
An instance of BNRItem will represent something that a person owns in the real world, like a laptop, a bicycle, or a backpack. In terms of Model-View-Controller, BNRItem is a model class. An instance of BNRItem stores information about a possession.
Once you have created the BNRItem class, you will populate the items array with instances of BNRItem instead of NSString.
Figure 2.10 A different class of items
Later in the book, ...