1. #Swift3Arch
Architecting Alive
Apps
Jorge D. Ortiz Fuentes
@jdortiz

2. #Swift3CA
A Canonical
Examples
Production

3. #Swift3CA
Agenda
★ Advanced Architecture Background
★ Application for Frameworks
★ Real World Example
★ Recommendations
★ Recap

4. Advanced Architecture

5. The Classics

6. #Swift3Arch
Clean Architecture: iOS
App
Delegate
View (VC) Presenter Interactor
Entity
Gateway
Connector

7. #Swift3Arch
Clean Architecture Layers
UI
DB
Preseters
Gateways
Use
cases
Entities
D
ependencies

8. #Swift3CA
View
class AddProgrammerViewController: UITableViewController, UITextFieldDelegate {
var presenter: AddProgrammerPresenter!
var connector: AddProgrammerConnector!
@IBOutlet weak var nameTextField: UITextField!
override func viewDidLoad() {
super.viewDidLoad()
presenter.viewReady()
}
@IBAction func cancel(_ sender: Any) { presenter.cancel() }
@IBAction func save(_ sender: Any) { presenter.save() }
}
extension AddProgrammerViewController: AddProgrammerView {
func display(title: String) { self.title = title }
func enableSaveButton(_ enable: Bool) { saveButton.isEnabled = enable }
}

9. #Swift3CA
Presenter
class AddProgrammerPresenter {
private let useCaseFactory: UseCaseFactory
weak var view: AddProgrammerView!
private var programmer = ProgrammerRequest() {
didSet { updateView() }
}
init(useCaseFactory: UseCaseFactory) { self.useCaseFactory = useCaseFactory }
func viewReady() { configureView() }
private func updateView() {
showTitle()
!// …
configureSaveAbility()
}
private func configureView() {
setUpName()
!// …
updateView()
}
private func showTitle() { view.display(title: programmer.name) }
}

10. #Swift3CA
Interactor
class AddProgrammerUseCase {
fileprivate let entityGateway: EntityGateway
fileprivate let request: ProgrammerRequest
fileprivate let completion: AddProgrammerCompletion
init(entityGateway: EntityGateway, request: ProgrammerRequest, completion:
@escaping AddProgrammerCompletion) {
self.entityGateway = entityGateway
self.request = request
self.completion = completion
}
}
extension AddProgrammerUseCase: UseCase {
func execute() {
let programmer = Programmer(…)
entityGateway.create(programmer: programmer) {
self.completion()
}
}
}

11. #Swift3CA
Entity Gateway
class InMemoryRepo {
var fetchNotifier: FetchProgrammersCompletion?
fileprivate var programmers = […]
}
extension InMemoryRepo: EntityGateway {
func create(programmer: Programmer, completion: @escaping
CreateProgrammerCompletion) {
programmers.append(programmer)
completion()
self.fetchNotifier?(programmers)
}
}

12. #Swift3CA
Connector
class AddProgrammerConnector {
let entityGateway: EntityGateway
init(entityGateway: EntityGateway) {
self.entityGateway = entityGateway
}
func assembleModule(view: AddProgrammerViewController) {
let useCaseFactory = UseCaseFactory(entityGateway: entityGateway)
let presenter = AddProgrammerPresenter(useCaseFactory: useCaseFactory)
view.presenter = presenter
view.connector = self
presenter.view = view
}
}

13. #Swift3CA
Factory
class UseCaseFactory {
let entityGateway: EntityGateway
init(entityGateway: EntityGateway) {
self.entityGateway = entityGateway
}
func addProgrammerUseCase(request: ProgrammerRequest, completion: @escaping
AddProgrammerCompletion) !-> UseCase {
return AddProgrammerUseCase(entityGateway: entityGateway, request:
request, completion: completion)
}
}

14. And What If?

15. #Swift3CA
Interacting with
Frameworks
Accounts
AddressBook
HomeKit
EventKit
HealthKit
Core Audio
Core Location
HomeKit
EventKit

16. The Secret Sauce

17. #Swift3CA
Injecting Dependencies
View
Presenter
UseCaseFactory
Entity
Gateway
Connector

18. Been There, Done
That

19. Dependency Inversion
Principle
High LowAbstract
Low

20. #Swift3CA
CloudKit
★ This is data source
using CloudKit
★ CloudKit is an
implementation
detail
★ NO leaky
abstractions
class CloudKitRepo {
let database: CKDatabase
let programmerRecord = "Programmer"
init() {
let container = CKContainer.default()
database = container.database(with: .private)
}
fileprivate func recordFrom(programmer: Programmer) !->
CKRecord {
let programmerID = CKRecordID(recordName:
programmer.id)
let record = CKRecord(recordType: programmerRecord,
recordID: programmerID)
updateRecordProperties(record: record, programmer:
programmer)
return record
}
}
extension CloudKitRepo: EntityGatewayProtocol {
func create(programmer: Programmer, completion:@escaping ()
!-> Void) {
let record = recordFrom(programmer: programmer)
database.save(record) { record, error in
guard error !== nil else {
NSLog("Save error:
(error!?.localizedDescription)")
return
}
DispatchQueue.main.sync { completion() }
}
}
}

21. #Swift3CA
Injecting Dependencies 2
View
Presenter
UseCaseFactory
Entity
Gateway
Connector
Framework

22. Real World Example

23. A Prototype

24. #Swift3CA
Meetinator
EventKit
HomeKit
Magic

25. #Swift3CA
Yes, but…

26. #Swift3CA
MQTT
Server
Suscribe
“/rooms/meeting1/colorlight”
Device
Raspberry
Pi
Device
Device

27. #Swift3CA
MQTT
Server
Publish
“/rooms/meeting1/colorlight”
{ “firetime”: …}
Device
Raspberry
Pi
Device
Device
iPhone

28. #Swift3CA
Another Approach
EventKit
CocoaMQTT MQTT
(JSON)
Mosquitto

29. Right Abstraction?

30. #Swift3CA
Any* Abstraction is
Better than No
Abstraction

31. Hints for Good
Abstractions

32. #Swift3CA
No References to
Framework

33. #Swift3CA
Use Your Own Data
Types

34. #Swift3CA
Events
struct MeetingEvent {
let id: String
var name: String
var startDate: Date
var endDate: Date
var hasLights: Bool
}

35. #Swift3CA
Use Your Own
Communication
(Delegates/Observer/Rx…)

36. #Swift3CA
Use Only What You
Need

37. #Swift3CA
Move Implementation
Details Into
Abstracted Type

38. Details

39. #Swift3CA
From Date to JSON
★ MQTT messages
contained JSON
★ firetime is a JSON
format date
let formatter =
ISO8601DateFormatter()
let command: [ String: String ] = [
"firetime":
formatter.string(from: fireDate),
"type": type.mqttActionType(),
]
let jsonData = try!
JSONSerialization.data(withJSONObject
: command, options:
JSONSerialization.WritingOptions())
as Data

40. #Swift3CA
Picky with Dates
★ HomeKit
HMTimeTrigger only
accepts times with
seconds = 0
private func fixFireDate(_ fireDate:
Date) !-> Date {
let calendar = Calendar.current
let fixedFireDate =
calendar.nextDate(after: fireDate,
matching: DateComponents(second: 0),
matchingPolicy: .nextTime)!
return fixedFireDate
}

41. #Swift3CA
Browse HomeKit
★ HomeKit offers several
abstractions in a
hierarchy
• Homes
• Rooms
• Accessories
• Services
• Triggers
★ Extract what you need
class HomeKitColorLight: NSObject, LightController
{
var delegate: LightControllerDelegate?
fileprivate let homeManager: HMHomeManager
fileprivate var primaryHome: HMHome?
func homeManagerDidUpdateHomes(_ manager:
HMHomeManager) {
primaryHome = homeManager.primaryHome
delegate!?.lightControllerReady(self)
}
private func searchFirstColorLight() !->
HMService? {
let lightbulbs =
primaryHome!?.servicesWithTypes([HMServiceTypeLightb
ulb])
let colorLightbulb = lightbulbs!?.first
{ (service) in
let characteristics =
service.characteristics.filter { (characteristic)
in
return
characteristic.characteristicType !==
HMCharacteristicTypeHue
}
return characteristics.count > 0
}
return colorLightbulb
}
}

42. #Swift3CA
Look for Events
★ EventKit allows
multiple calendars
★ Avoid that
complexity
fileprivate func fetchMeetingCalendar() {
guard status !== .ready else { return }
let calendars =
eventStore.calendars(for: .event)
let calendar = calendars.filter { $0.title
!== meetingCalendarTitle } .first
if let calendar = calendar {
meetingCalendar = calendar
} else {
meetingCalendar =
EKCalendar(for: .event, eventStore:
eventStore)
if let meetingCalendar =
meetingCalendar {
meetingCalendar.title =
meetingCalendarTitle
meetingCalendar.source =
eventStore.defaultCalendarForNewEvents.source
do {
try
eventStore.saveCalendar(meetingCalendar,
commit: true)
} catch let error as NSError {
NSLog("Error: (error)")
}
}
}
}

43. #Swift3CA
Authorization
★ EventKit requires
Authorization to
access the data
class EventKitEventProvider {
enum Status {
case ready, accessDenied, unknown
}
let eventStore: EKEventStore
var status = Status.unknown
init() {
eventStore = EKEventStore()
checkAccessToEvents()
fetchMeetingCalendar()
}
private func checkAccessToEvents() {
switch
EKEventStore.authorizationStatus(for: .event) {
case .authorized:
status = .ready
case .notDetermined: !// First time access
requestAccessToEvents()
case .denied, .restricted:
status = .accessDenied
}
}
private func requestAccessToEvents() {
eventStore.requestAccess(to: .event)
{ (granted: Bool, error: Error?) in
!// …
}
}
}

44. #Swift3CA
extension LightControllerAction {
func homeKitColor() !-> UIColor {
let color: UIColor
switch(self) {
case .start: color = UIColor.green
case .warn: color =
UIColor.orange
case .end: color = UIColor.red
case .off: color = UIColor.black
}
return color
}
func sceneName() !-> String {
let name: String
switch(self) {
case .start: name = "Go green"
case .warn: name = "Go orange"
case .end: name = "Go red"
case .off: name = "Go off"
}
return name
}
}
Extend like a Boss
extension LightControllerAction {
func mqttActionType() !-> String {
let action: String
switch self {
case .start:
action = "start"
case .warn:
action = "warn"
case .end:
action = "end"
case .off:
action = "off"
}
return action
}
}

45. Recap

46. #Swift3CA
Recap
★ IoT is cool!
★ Advanced architectures can also be applied
to apps with frameworks
★ Use abstractions
★ YES, I mean it: Use abstractions

47. Thank
You!

48. @jdortiz
#Swift3CA