This document outlines the Model-View-ViewModel (MVVM) pattern and compares it to related patterns like MVC. It defines the key components in MVVM - the model, view, and view model. The view model acts as an adapter between the model and view, containing business logic and handling data binding. Benefits of MVVM include testable view models and a cleaner separation of concerns between the view/controller and underlying data/logic. ReactiveCocoa is mentioned as a framework that can provide the data bindings in MVVM. Core Data is one option for building the model/data layer.

1. MVVM
Robert Brown
@robby_brown
@robert_brown
@rob-brown

2. Outline
1. Core Data
2. Reactive Cocoa
3. MVVM

3. Core Data

4. What is Core Data?
Intimidating
An amazing data persistence framework
Not a database

5. Core Data Layers
XML SQLite Binary In Memory Custom
NSPersistentStore
NSPersistentStoreCoordinator NSManagedObjectModel
NSManagedObjectContext
NSManagedObject
Application
NSManagedObject Subclass

6. Core Data Stack
Persistent Store
Coordinator
Managed Object
Context(s)
Persistent Store(s)
Managed
Object Model

7. More on Core Data
Intro to Core Data
Core Data: Data Storage Management for iOS, OS X,
and iCloud
RBCoreDataStack

8. Reactive Cocoa

9. What is Reactive Cocoa?
Made by GitHub
A functional reactive programming (FRP) framework
Provides the bindings in MVVM

10. What is Reactive Cocoa?
Binds properties together
Eliminates the need for mutable state
UI updates automatically as data changes

11. More on Reactive Cocoa
Intro to Reactive Cocoa
Functional Reactive Programming on iOS
ReactiveCocoa

12. MVVM

13. What is MVVM?
Model-View-ViewModel
A variant of MVC
Uses an adapter between the view and model

14. What is MVVM?
View
View
Model
Model
Owns Owns
UpdatesUpdates

15. What is MVVM?
Data Model
ViewModel Network
ViewController
View
Data Storage

16. Application Stack
ViewModel Network
ViewController
View
SQLite Binary In Memory Custom
NSPersistentStore
NSPersistentStoreCoordinator NSManagedObjectModel
NSManagedObjectContext
NSManagedObject
NSManagedObject Subclass
XML

17. Model
Represents the data layer
Can be built with any technology
Ex. Core Data, SQLite, JSON, PList, memory-only

18. View
Handles layout and presentation of data
In iOS, the “View” refers to both UIViews and
UIViewControllers

19. ViewModel
An adapter between the View and Model
Contains all the business logic
Uses bindings to pass data around

20. ViewModel
Acts like a model
Hides the real model logic from the view

21. ViewModel
Some responsibilities:
Kick off network and database requests
Show/hide information
Data/number formatting
Localization

22. Benefits of MVVM
View models are testable
View models can be used like models
View models are (mostly) platform-agnostic
View and view controllers are simpler

23. Related Patterns
Model Operation View Event (MOVE)
Model View Presenter (MVP)
Presentation Model (PM)

24. Questions?

25. Demo

26. Want to Learn More?
ReactiveViewModel
Functional Reactive Programming on iOS
Wikipedia

27. Want to Learn More?
!
Ash Furrow
C-41
Functional Reactive Pixels