Core Data on iOS

Dhwanil Karwa

Topics

• What is Core Data?

• Framework Overview

• Using Core Data

• Demo

1

What is Core Data?• It is not a database.

• It is not an Object Relational Mapping framework.

• Apple explains it as “Core Data is a Schema driven object graph management and persistence Framework”

• It creates a layer between database and UI.

1

• Performs CRUD operations

• Queries values using NSPredicate

• You don’t define the identity primary keys, only give relationships.

What is Core Data?

• Before Core Data, developers had to work with Sqlite3 to save data.

• Handling CRUD operations was difficult.

• User was responsible to check if saved data matched the schema.

• Means you are writing your own persistence Layer

• Using Core Data hides Sqlite3

Why learn Core Data?

Storage Options

• Binary

• In-memory

• XML only on Mac OS X

• Sqlite

SQLITE CORE DATA

Bulk Operations YES NO

Automatic Object Population NO YES

Custom SQL YES NO

Select certain fields YES NO

Automatic Migration NO YES

Less Complex Code NO YES

Core Data vs. SQLite3

Core Data M-VC

Controller View

Model

Core Data

ImplementsObserver

Controller implements Strategy for the View

Core Data Stack

Heart of Core Data

• NSManagedObjectModel

• NSPersistentStoreCoordinator

• NSManagedObjectContext

NSManagedObjectModel

• Schema for Models

• Entity, Attributes, Relationships

• Fetch Requests

• Validation

NSManagedObjectModel

• Integer, Decimal, Float, Double

• Boolean

• Date

• String

• Binary Data

• Transformable

Attribute Types

NSManagedObjectModel

• NSSet not NSArray

• One to One

• One to Many

• Many to Many

• Delete Rules

• Nullify, Cascade, Deny

Relationships

NSManagedObjectModel

NSPersistentStoreCoordinator• Coordinates access to one or more

persistent stores.

• Depends on Managed Object Model

• Set store options

NSPersistentStoreCoordinator

NSManagedObjectContext

Core Data Model Inspector

Core Data Model Inspector

Save Objects

NSFetchRequest

DEMO

References

• Apple Developer. 2012. Core Data Programming Guide

https://developer.apple.com/library/mac/documentation/cocoa/conceptual/coredata/cdProgrammingGuide.html#//apple_ref/doc/uid/TP30001200-SW1

• Burkepile Adam. 2013.http://www.raywenderlich.com/934/core-data-tutorial-for-ios-getting-started

Questions?

Thank You