Book Image

Core Data iOS Essentials

Book Image

Core Data iOS Essentials

Overview of 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.

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Core Data iOS Essentials
Apr, 2011 | 340 pages
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Table of Contents (19 chapters)
Core Data iOS Essentials
Core Data iOS Essentials
Credits
Credits
About the Author
About the Author
Acknowledgement
Acknowledgement
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Overview
Overview
Prerequisite
A brief history
Source code
Shall we begin?
2
Understanding Core Data
Understanding Core Data
Core Data
Data Model
Model View Controller (MVC)
Core Data API
Overview of the application: Sales Record System for a Departmental Store
Entity Relationship Diagram
An application output sample
Automatic Master Product Update
Summary
3
Understanding Objective-C Protocol and Table View
Understanding Objective-C Protocol and Table View
Protocol
Creating a sample application using a protocol and a delegate
Introduction to Table View
Creating an application to display Table View cells
Adding names to the Table View
Summary
4
Designing a Data Model and Building Data Objects for Customers
Designing a Data Model and Building Data Objects for Customers
Creating a new project
Designing the data model
Building data objects for the Customer entity
Understanding code of autogenerated files
Summary
5
Creating, Listing, and Deleting Names of Customers
Creating, Listing, and Deleting Names of Customers
Splitting the task into two modules
Creating a module to save and delete a customer's name
Key value coding (KVC)
Implementing the methods of the NSFetchedResultsControllerDelegate protocol
Running the project
Summary
6
Creating, Listing, Displaying, and Deleting Records of Customers
Creating, Listing, Displaying, and Deleting Records of Customers
Understanding multiple managed object context
Applying the concept of multiple managed object context in our application
Enhancing our application to save, list, display, and delete customer information
viewDidLoad method
cell AtIndexPath method
didSelectRowAtIndexPath method
addCustomer method
addcustomerController method
Summary
7
Updating and Searching Records of Customers
Updating and Searching Records of Customers
Applying the update feature
Using KVO to know what has been updated
Running the project
Applying search facility
Understanding NSPredicate
Removing the keyboard after selecting a customer's name
Using Predicate Builder for creating a search criterion
Summary
8
Entering, Saving, Listing, and Deleting the Records of the Products Sold to the Customers
Entering, Saving, Listing, and Deleting the Records of the Products Sold to the Customers
Adding the product entity to the Data Model
Relationship
Establishing a relationship between the Customer and the Product entities
Building the data object for the Customer and the Product entities
Entering the information of the products sold to the customers
Creating a module to develop an interface to enter the product information
Developing a module to create a menu for manipulating the product information
Creating a module to connect the Product's menu to the rest of the project
Running the project
Summary
9
Entering, Displaying, and Deleting the Stock
Entering, Displaying, and Deleting the Stock
Adding the MasterProduct entity to the Data Model
Storing the image of the MasterProduct
Building the data object for the MasterProduct entity
Maintaining the MasterProduct information
Summary
10
Editing the Stock Information
Editing the Stock Information
Module to connect the MasterProduct's menu to the rest of the project
Running the application
Module to modify the information of the master product
Summary
11
Displaying the Products for Sale and Updating the Stock
Displaying the Products for Sale and Updating the Stock
Displaying the products available for sale
Updating the stock
Automatically updating the quantity of the product in the MasterProduct entity
Versioning
Migrations
Summary
Appendix
Appendix

Key value coding (KVC)

The Core Data uses KVC to store and retrieve data from its managed objects. NSManagedObject supports the key value methods valueForKey: and setValue:forKey: for setting and retrieving attribute values from the managed object respectively.

Key value methods

The two key value methods that are widely used for setting and retrieving values of the attributes of the managed object are explained in the following sections.

The -valueForKey: method

The method -valueForKey: is a generic accessor to retrieve the specified attribute value from a managed object.

For example, let's say we have a managed object (Customer) and it has an attribute called name; we can obtain the value of the name attribute with the following:

NSString *custName = [managedObject valueForKey:@"name" ];

The value of the attribute name is retrieved from the managed object and is assigned to the NSString instance custName.

Similarly, the code used in the cellForRowAtIndexPath method in the RootViewController...

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