In the middle of difficulty lies opportunity.
In Chapter 6, “Views,” you started building the Item view as the concept of passing managed objects around the application was demonstrated. Its primary focus introduced text fields as a means to edit managed objects. This chapter explains how to create special text fields that have a Core Data-driven
UIPickerView as the input view. The purpose of a picker text field is to make selecting from predefined values, such as a shop aisle, as easy and fast as possible.
Picker views make it easy for a user to relate managed objects to each other. In Groceries, this makes picker views ideal for setting the item relationships