Objective-C Fundamentals

94 CHAPTER 4 Storing data in collections
4.5 Summary
Object-oriented programming, as implemented by Objective-C, has many advantages
to the application developer over procedural-based languages such as C. The ability to
combine data with logic means that you can encapsulate common functionality and
avoid developing the same algorithms for enumeration, searching, and other actions
in each application you develop. This enables you to concentrate on differentiating
your product and to avoid common types of bugs. Nothing comes for free, however,
and you’ve seen a number of limitations where the procedural world meets the objectoriented,
such as the challenges of testing for object equality or storing values of primitive
data types such as int in an object.
By using the reusable classes provided by Foundation Kit, you were quickly able to
modify the Rental Manager application from being hardcoded to being a dynamic
and rather easily modified application. Rather than requiring code changes to alter
the city-to-image mappings, the updated version, which uses an NSDictionary, can
easily be updated from a plist, a file on the internet, or any other source the developer’s
imagination dreams up.
In chapter 5, we cover some of the more technical aspects of Objective-C by learning
how you can define and implement your own classes. You do this by turning the
RentalProperty structure into an Objective-C class, so your sample application is
truly object oriented. This is the last major C-style holdover left in your Rental Manager
application.