This document provides an overview of Core Data including defining a data model with entities, attributes, and relationships. It also covers creating, fetching, updating, and deleting managed objects using Core Data and the managed object context. Key aspects of Core Data like the Core Data stack, persistent container, and data model editor are explained.

1. Core data
Allan Shih

2. Agenda
● Overview
● Core Data stack
● Data Model Editor
○ Entity
○ Attributes
○ Relationships
● Creating and Saving Managed Objects
● Fetching Objects
● Reference

3. Core Data Overview
● Core Data is a framework that you use to manage the model layer objects
in your application.
● Core Data's focus is on objects rather than the traditional table-driven
relational database approach.
● Core Data typically decreases by 50 to 70 percent the amount of code you
write to support the model layer.

4. Different between SQLite and Core Data
● SQLite
○ SQLite is, as advertised, lightweight.
○ SQLite uses less memory and storage space.
○ SQLite can be tedious and error-prone to code.
○ SQLite is supported on Android and Microsoft Windows Phone.
● Core Data
○ Longer learning curve: it takes some study to understand.
○ Objects are easier to work with.
○ Underlying storage details are handled atomically (support for iCloud).
○ Undo and Redo features.

5. Core Data Stack

6. Create a project with Core Data

7. ManagedObjectContext for iOS 8+9 (AppDelegate.swift)

8. PersistentContainer for iOS 10 (AppDelegate.swift)

9. Data Model Editor

10. Entity

11. Attributes

12. Attribute Options

13. Attribute Type

14. Attribute Type
Name Value Validation
Undefined - -
Integer 16 -32768 ~ 32767 Range, Default Value
Integer 32 -2147483648 ~ 2147483647 Range, Default Value
Integer 64
–9223372036854775808 ～
9223372036854775807
Range, Default Value
Decimal base-10 arithmetic Range, Default Value
Double 64-bit floating-point number Range, Default Value

15. Attribute Type
Name Value Validation
Float 32-bit floating-point number Range, Default Value
String String
String Length, Default Value,
Regular expression
Boolean true or false Default Value
Date Date Date range, Default Date
Binary Data NSData -
Transformable
NSValueTransformer to convert
to/from NSData
-

16. Allows External Storage

17. Person’s Relationships

18. Address’s Relationships

19. No inverse relationship

20. Inverse relationship

21. Data Model Graph

22. One-To-Many Relationships

23. Many-To-Many Relationships

24. Delete Rules

25. Delete Rules - No Action

26. Delete Rules - Nullify

27. Delete Rules - Cascade

28. Delete Rules - Deny

29. Entity Inheritance

30. Define a Data Model (SOP)

31. Create NSManagedObject Subclass

32. Managed entities

33. Save to CoreDatas Group

34. CategoryModel+CoreDataClass

35. CategoryModel+CoreDataProperties

36. Creating Managed Objects
let entity = NSEntityDescription.insertNewObject(
forEntityName: "Groups",
into: managedObjectContext) as! Groups
entity.filterGroupKey = filterGroup.filterGroupKey
entity.filterGroupName = filterGroup.filterGroupName
entity.rank = Int16(filterGroup.rank ?? 0)

37. Saving NSManagedObject Instances
do {
try managedObjectContext.save()
} catch {
let nserror = error as NSError
NSLog("Unresolved error (nserror), (nserror.userInfo)")
abort()
}

38. Fetching NSManagedObject Instances
let fetchRequest = NSFetchRequest<Groups>(entityName: "Groups")
do {
let fetchedGroups = try
managedObjectContext.fetch(fetchRequest)
} catch {
fatalError("Failed to fetch groups: (error)")
}

39. Filtering Results
let fetchRequest = NSFetchRequest<Groups>(entityName: "Groups")
let groupName = "Figures"
fetchRequest.predicate = NSPredicate(format: "filterGroupName ==
%@", groupName)
managedObjectContext.fetch(fetchRequest)

40. Sorting Results
let fetchRequest = NSFetchRequest<Groups>(entityName: "Groups")
let sortDescriptor = NSSortDescriptor(key: "rank", ascending: true)
fetchRequest.sortDescriptors = [sortDescriptor]
managedObjectContext.fetch(fetchRequest)

41. Updating Objects
let fetchRequest = NSFetchRequest<Groups>(entityName: "Groups")
fetchRequest.predicate = NSPredicate(format: "filterGroupKey ==
%@", groupKey)
let groups = managedObjectContext.fetch(fetchRequest)
if groups.count > 0 {
groups[0].rank = 10
}

42. Deleting Objects
let fetchRequest = NSFetchRequest<Groups>(entityName: "Groups")
fetchRequest.predicate = NSPredicate(format: "filterGroupKey ==
%@", groupKey)
let groups = managedObjectContext.fetch(fetchRequest)
for group in groups {
managedObjectContext.deleteObject(group)
}

43. Reference
● The Swift Programming Language (Swift 3.0.1)
● Core Data Programming Guide
● iOS Data Storage: Core Data vs. SQLite
● Core Data Relationships and Delete Rules
● Core-data-fundamentals
● 【Swift】Core Dataの使い方。