Core Data is a powerful Data Model framework, a framework for object management and persistence. It helps developers to manage the lifecycle of objects and object graphs.

1. All You Need to Know about Core Data iPhone SDK
Core Data is a powerful Data Model framework, a framework for object management
and persistence. It helps developers to manage the lifecycle of objects and object
graphs. It can lower the memory overhead of application, increase responsiveness
and reduce code. It comes up with classes those are abstractions for normal
functions, including create, delete, select and update. It was ported from Mac OS X
to the iPhone with the 3.0 iPhone SDK release.
The simple reason for why Core Data is it allows developer to develop complicated
applications with very less code. To develop complicated applications, it takes far less
code and time than it would take without core data.
Core Data iPhone SDK Features:
1. Built-in management of undo and redo in addition to basic text editing
2. Automatic validation of property values
3. It maintains the consistency of relationships among objects
4. Is Organizing data in memory and in the user interface
5. Support for storing objects in external data cache
6. Grouping and filtering
7. It provides optional integration with Cocoa bindings to
8. It supports automatic user interface synchronization
Core Data objects:
1. Managed Object Model:
Managed Object Model is similar as the database schema. It is a class that contains
Entities that are stored in the database. Visual editor is used to set up what these
entities are in the database, what their attributes, and how they relate to each other
(relationships). However, it can also be done with code.
2. Managed Object Context:
Managed Object Context is a single object space in an application.
Its main responsibility is to manage a group of managed objects. It is also the most
important of all. Mainly, whenever developer needs to select objects, insert objects,
or delete objects, methods are called on this context.
Persistent Store Coordinator:
Core Data provides three types of disk-based persistent store—
1. XML (not available on iOS)
2. Atomic
3. SQLite and an in-memory store
Core Data also provides the binary store type as a built-in atomic store and also
provides Custom store types to create own atomic store types.
Persistent store coordinator is similar as the database connection. It act as mediate
between provided persistent store and the managed object context. Context can
access a model through this coordinator.
Core Data classes:
NSFetchrequest
NSMAngedRequest
NSMANAgerdObjectContext
NSManagedObjectModal

2. NS Persistent Store Coordinator
NS Perdicate
Core Data iPhone SDK Limitations
1. Core Data is not a database but a data store.
2. Core Data provides a structure for change tracking and management and for
storing objects to storage and retrieving them from storage.
3. Core Data does not remove the need to write code. But it provides a better way.
While it is possible create a small application only using the Xcode data modeling tool
and Interface Builder, but for more real-world &complicated applications developer
will need to write code.
Core Data iPhone SDK how it performs:
As Core Data is a rich framework for object management and persistence, it is
capable of dealing with large volumes of data(objects). For a very small & simple
application it may be add some overhead, however it adds important functionality.
With small overhead, even a simple application is able to do undo and redo,
validation, and provides the ability to save objects to store. As the complexity of an
application increases, so the proportionate overhead by Core Data decreases and at
the same time the benefit increases. But it needs consideration of memory
management and how to fetch data from a persistent store.
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