Core Data iOS Essentials

By B.M.Harwani
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  1. Overview

About this book

Core Data is the essential ingredient in data driven iOS apps. It's used for storing, retrieving, and manipulating application data in databases, XML, and binary formats. It's an essential component for iPhone, iPod Touch, and iPad apps.

Core Data Essentials provides a clear, readable guide to the most useful aspects of Core Data. Built around a realistic example app, the book showcases the most important aspects of Core Data development in the context of a complete, functioning app written in Objective C.

The book starts with a tour of how the app works. Then you'll see how to easily display data using the Table View. You'll learn how to develop an appropriate data model that fits the needs of your app, then implement that model as updatable data objects. You'll see how to update data and build relationships between objects and learn how Core Data can work with search, and how to provide your users with friendly data editing features.

Publication date:
April 2011
Publisher
Packt
Pages
340
ISBN
9781849690942

 

Chapter 1. Overview

This book is a practical guide to help you in developing Data-Driven iPhone applications using Core Data. The tremendous success of iPhone has increased the demand of mobile applications. Besides the Game-based applications, there is a huge market for the data-driven mobile applications too. The focus of this book is to make you understand how the Core Data, Apple's persistence framework, is used for developing data-driven mobile applications.

 

Prerequisite


This book assumes that you have a basic understanding of the iPhone SDK and you also know the basics of iPhone SDK programming.

To better understand the concept of Core Data, you should:

  • Have a good understanding of the Objective-C protocol and the delegation pattern

  • Be familiar with data source patterns, such as UITableView and UITableViewDataSource, for the purpose of displaying information

Even if you're not aware of these two concepts, Chapter 3, Understanding Objective-C Protocol and Table View and Chapter 4, Designing a Data Model and Building Data Objects for Customers of the book are focused to get you acquainted with them. That is why the two chapters are self-contained and each chapter presents an individual application.

 

A brief history


The iPhone as we all know is an integrated cellular telephone and media player developed and marketed by Apple. It has become very popular in the past few years because of its amazing features. Looking at its huge number of users, developers around the world are attracted to develop applications for this unique device. Developers realized that besides games, there is a huge market of data applications for iPhone device. The attraction of creating data applications for iPhone device resulted into development of the Core Data framework. But the question is where did Core Data come from?

Core Data was first developed at NeXT Computer as the DBKit framework in 1992, which then became the Enterprise Object Framework (EOF) in 1994.

Enterprise Object Framework (EOF)

EOF is an object-relational mapping (ORM) framework that provides a mechanism for accessing the data as an object-oriented class structure. It is well-designed and encourages Model View Controller (MVC) design patterns. It also simplifies the tedious job of creating an application's data model. EOF is not just a framework, it is also a tool that helps in creating the application's data model visually — the task that was previously done by creating Objective-C classes. Besides this, the framework handles all the work involved in persisting the data to a SQL database, flat file, or any other data store. Based on object-oriented architecture, EOF is very flexible to use too. The roots of the Core Data framework come from the Enterprise Objects Framework (EOF).

Core Data

Core Data is part of the Cocoa API in Mac OS X first introduced with Mac OS X 10.4 Tiger and for the iOS with iPhone SDK 3.0. It is a powerful data model framework that was specifically designed to provide local data storage for Cocoa applications. The modeling functionality of Core Data is integrated right into XCode, so there's no need to switch back and forth between the IDE and modeler. With interface builder, it allows developers to quickly create a user interface (known as the views of the application in MVC terminology) without writing a single line of code. It is also the most effective solution to data persistence and allows us to persist our data to any number of different storage mediums, which includes storing data as XML, in binary files, or in an embedded SQLite database. The data modeling tool of Xcode allows us to define our application's data model graphically, which can be easily accessed through code. Instances of the entities defined in the data model are then managed by the Core Data framework and stored to a storage medium such as an XML file or SQLite database.

Now the question arises, what is Xcode and why we are using it for developing Core Data applications?

Why use Xcode?

Xcode is Apple's most comprehensive Software Development Kit (SDK), and it provides an environment for developing the applications for iPhone. It is a highly customizable integrated development environment (IDE) that includes compilers and applications, together with an extensive set of programming libraries and interfaces. It is a powerful source editor and a graphic debugger too. While developing applications with XCode, it gives us an option to enable a checkbox for enabling Core Data support. On selecting the checkbox, Xcode automatically creates code for us that make the task of developing core data applications quite easy.

 

Source code


The source code of the book is available at the URL specified in the Preface of the book.

You'll find chapter-wise code bundle in the ZIP file. The book is so organized that it guides you to develop a data-drive application step-by-step. That is, by the end of the book, you'll be having a complete data-driven running application with you. In case, you want to run the end product directly, follow the below given steps:

  1. 1. Unzip the source bundle of the last chapter, Chapter 11, Displaying the Products for Sale and Updating the Stock on your local Mac.

  2. 2. Open Xcode, go to File | Open from the menu, and browse to the unzipped bundle of Chapter 11, Displaying the Products for Sale and Updating the Stock. In the prob folder, select the prob.xcodeproj file followed by clicking on the Open button.

  3. 3. Select the Build and Run icon from the Xcode project window to run the application. You'll get the main view of the application as shown in the following image. But the application is not yet ready to run until we define the photos of the master products (products that we are going to sell through application).

  4. 4. To define photos of the master products in iPhone Simulator, go to Home and then click on the Photos icon (refer to the given image (a)).

  5. 5. We get the Albums page as shown in image (b). Because we have not created any photo album yet, the figure displays the message, No Photos.

  6. 6. Drag the first image, IMG_0000.JPG provided in the code bundle of Chapter 11, Displaying the Products for Sale and Updating the Stock onto the simulator screen. Tap on the image and hold down the mouse on the image until the popover comes up, as shown in image (c). Click on the Save Image button to save the image.

  7. 7. Repeat the procedure for the other three images (IMG_0001.JPG, IMG_0002.JPG, IMG_0003.JPG). After saving the four images, the simulator will display the images as shown in image (a).

  8. 8. On clicking back to Photos, we find that an album Saved Photos appears with one of the images considered as the icon of the photo album (image (b)). The number (4) in parenthesis represents that there are four images in this photo album.

  9. 9. Now, our application is completely ready for execution. For any guidance regarding operating the application, refer to the An application output sample section in Chapter 2, Understanding Core Data.

 

Shall we begin?


After following how our book will proceed, let us now get ready to dive in. Get ready for the introduction of Core Data and the step-by-step journey to understand its different concepts and applying them practically in developing a data-driven mobile application.

About the Author

  • B.M.Harwani

    B.M.Harwani is the founder and owner of Microchip Computer Education (MCE), based in Ajmer, India that provides computer education in all programming and web developing platforms. He graduated with a BE in computer engineering from the University of Pune, and also has a 'C' Level (master's diploma in computer technology) from DOEACC, Government Of India.

    Being involved in the teaching field for over 16 years, he has developed the art of explaining even the most complicated topics in a straightforward and easily understandable fashion. He has written several books on various subjects that includes JSP, JSF, EJB, PHP, .Net, Joomla, jQuery, and Smartphones. He also writes articles on a variety of computer subjects, which can be seen on a number of websites. To know more, visit his blog, http://bmharwani.com/blog.

    The list of books written by B.M.Harwani are Programming & Problem Solving through C (BPB, 2004), Learn Tally in Just Three Weeks (Pragya, 2005), Data Structures and Algorithms through C (CBC, 2006), Master Unix Shell Programming (CBC, 2006), Business Systems (CBC, 2006), Practical Java Projects (Shroff, 2007), Practical Web Services (Shroff, 2007), Java for Professionals (Shroff, 2008), C++ for Beginners (Shroff, 2009), Practical ASP.NET 3.5 Projects (Shroff, 2009), Java Server Faces—A Practical Approach for Beginners (PHI Learning, 2009), Practical JSF Project using NetBeans (PHI Learning, 2009), Foundation Joomla (Friends of ED, 2009), Practical EJB Projects (Shroff, 2009), Data Structures and Algorithms in C++ (Dreamtech Press, 2010), Developing Web Applications in PHP and AJAX (Tata McGraw Hill, 2010), and jQuery Recipes (Apress, 2010).

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