core data ios
Umakanta Sahoo
iOS Team @THBS
What is core data ?
-
part of the Cocoa API
-
introduced in the iPhone
SDK 3.0
-
object-relational framework
-
Provides automatic data persistence
-
Efficient access
Why use Cora Data ?
Efficiency
Core Data Architecture
-
Managed Object
-
Managed Object Context
-
Data storage
-
Modeling Data
Managed Object
-
NSManagedObject
The
individual data obj in your class represented by a class
NSManagedObject
Managed Object Context
-
NSManagedObjectContext
- Core Data's scratch pad of your projects
- tracks changes to modal properties
- handles actions on your data
- central point
we work with, when we will do all things
Data storage
-
NSPersistentStore
- Data stored
in a Sqlite Database.
-
Core data
sits on the top of this layer
-
Schema and
data store in a file
in a special
format
Persistent Store Coordinator: database connection.
- Here’s where you set up the actual names and locations of what databases will be used to store the objects, and any time a managed object context needs to save something it goes through this single coordinator.
Modeling
our Data
- NSManagedObjectModel
- Graphically designed in xcode and you can see how they are connected to each other.
-
ManagedObjectModel describes
all these obj
→ Entity
→ relationship
-
We can define behavior with this object.
-
-
It use all these information in a managedObjectModel to create a store file.
Fetching Data
-
NSFetchRequest
-
how you access and save data
-
Flexible and powerful
-
very simple to use. All you have to decide what to fetch, where to fetch from and how you want to brought back to code
Easy as 1,2,3.
Types
There are bunch of ways how you can fetch
- Faulting
- prefetching
- batching
- partial faulting
- Aggregates
Faulting :
partial Faulting : 
Pre Fetching : 
Batching : 
Aggregates :
-
Basically data summaries.
-
In-database aggregates :
- sum
- count
- min
- max
- average
Working with UI Kit
Threading
practicing safe object ownership
Core data uses a policy of isolation
- one managedObject per thread
- never pass managedObject between threads
- be careful passing data between thread
- Prefer object-id if you pass anything
core data ios
By Torry Harris Business Solutions
