iOS Programming: The Big Nerd Ranch Guide

Creating and Using Keys

When an image is added to the store, it will be put into a dictionary under a unique key, and the associated BNRItem object will be given that key. When the BNRDetailViewController wants an image from the store, it will ask its item for the key and search the dictionary for the image. Add a property to BNRItem.h to store the key.

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The image keys need to be unique in order for your dictionary to work. While there are many ways to hack together a unique string, you are going to use the Cocoa Touch ...