Clear the UIViewController Mess

@giorgionatili#MobileTea

Clean up the MVW

messa journey into the abomination of MVC

architecture on iOS

@giorgionatili#MobileTea

Who am I?

Technical Leader and Agile Coach·

Front-end Developer (test first!)

Mobile Developer (iOS, Android, Hybrid with Cordova, c++)

Organizer of Mobile Tea and New England Software

Engineer meetups

Mobile and devices instructor at General Assembly

the mobile dude!

@giorgionatili#MobileTea

on stage

The

UIViewController

spaghetti monster

The invincible

delegates

The wild seguesfor tonight only!

NO.1

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It's not our fault!

Someone else designed the framework!

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SmallTalk MVC

courtesy of http://hollance.github.io/

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iOS MVC

courtesy of http://hollance.github.io/

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Architecture horrors!

What’s Wrong with This?

Controllers are not

just controllers (the

class name should

suggest this)

Controllers are to

much tied in the view

(aka IBAction and

IBOutlet)

UI element s are

configured in the

viewDidLoad

Location services,

map services, etc. are

normally used in the

controller (delegates

arena)

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Xcode Defaults

The workflow of the interface builder brings you to do a mess!

With IBOutlet how can we

resist to configuring UI

items in the viewDidLoad?

How can we resist to

configuring segues in the

interface builder?

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Why sucKh a Poor Design?

speeds up the development

decreases the learning curve

reduces the amount of code to write

More often misused and sometimes abused, however:

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But the architects were right!

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...we still can clean up the mess!

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Cleaning Side Effects

97%43%

Reduced size of controllers, improved testability, increased

code base

code will increase

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VIPER

DECOUPLING LOGIC

FROM UI

PROPER DATA HANDLING

REUSABLE CODE

PONSOS

ALL WELCOME!

SPLIT IN MULTIPLE LAYERS

View Interactor Presenter Entity Routing

CLI support

http://bit.ly/viper-ios

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View

Handle events invoking presenter’s methods

Exposes a very precise interface completely UI agnostic

The view is passive, it waits the presenter to render data

It’s no longer a Mess View Controller

UI items configuration is now delegated to UIView subclasses

@giorgionatili#MobileTea

Interactor

represents a single use case in the app

contains the logic to manipulate entities (local

and remote)

communicate with the view through the presenter

It’s a wrapper around the data communication layer

Business logic is not anymore in the

controller

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Presenter

gathers user input and send the request to the interactor

Receives results from the interactor as simple data structures

Updates the view

Orchestrates the communication and

business logic

The controller logic is now completely

decoupled

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Entity(ies)

It’s a model object manipulated by the interactor

An entity is never passed around the app

The entities are simple and maintainable

CoreData, services, etc. are no longer mixed up

with the view

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Routing

handles navigation from one view to another

owns the UIWindow and installs the

view(controller) in the window

knows how to react to presenter “signals”

Communication handled through NotificationCenter and

Key-Value Observing

Segues and present/push VierController(s) are not

anymore in the view

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Files Structure

.objc +-- DataManager | +-- VIPERDataManager.h | +-- VIPERDataManager.m +-- Interactor | +-- VIPERInteractor.h | +-- VIPERInteractor.m +-- Presenter | +-- VIPERPresenter.h | +-- VIPERPresenter.m +-- ViewController | +-- VIPERViewController.h | +-- VIPERViewController.m +-- WireFrame | +-- VIPERWireFrame.h | +-- VIPERWireFrame.m +-- Protocols | +-- VIPERProtocols.h

swift +-- DataManager | +-- VIPERDataManager.swift +-- Interactor | +-- VIPERInteractor.swift +-- Presenter | +-- VIPERPresenter.swift +-- ViewController | +-- VIPERViewController.swift +-- WireFrame | +-- VIPERWireFrame.swift +-- Protocols | +-- VIPERProtocols.swift

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Q and A