A TASTE OF MVVM + RXSWIFT

aka THE 100TH TALK ABOUT MVVM, RXSWIFT ! WHY DO PEOPLE KEEP TALKING ABOUT THIS ?

ABOUT > [email protected] > https://github.com/onmyway133 > https://github.com/hyperoslo

OBJECT ORIENTED PROGRAMMING > characteristics > action

PROJECT MANAGER > Designer > Tester > Scrum Master > Developer -> Freelancer

MVC Source https://www.raywenderlich.com

UIVIEWCONTROLLER func viewDidLoad() var preferredStatusBarStyle: UIStatusBarStyle { get } UITableViewDataSource var presentationController: UIPresentationController? { get } func childViewControllerForScreenEdgesDeferringSystemGestures() -> UIViewController? func didMove(toParentViewController parent: UIViewController?) var systemMinimumLayoutMargins: NSDirectionalEdgeInsets var edgesForExtendedLayout: UIRectEdge var previewActionItems: [UIPreviewActionItem] var navigationItem: UINavigationItem var shouldAutorotate: Bool ...

VIPER View Interactor Presenter Entity Routing

FCPN Functional Controller Presenter Navigator

CRSC Clean Reactor Store Coordinator

MRRI Megatron Router Reactive Interactor

let buzzWords = [ "Model", "View", "Controller", "Entity", "Router", "Clean", "Reactive", "Presenter", "Interactor", "Megatron", "Coordinator", "Flow", "Manager" ] let architecture = buzzWords.shuffled().takeRandom() let acronym = architecture.makeAcronym()

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ARCHITECTURE > Separation of concerns > Communication pattern > Comfortable to use

SAVING PRIVATE VIEWCONTROLLER

MVVM source https://www.raywenderlich.com

MVVM > Self contained > Testable > Good enough. Comfortable. > Improve existing ViewController

synchronously class ProfileController: UIViewController { override func viewDidLoad() { super.viewDidLoad() let viewModel = ViewModel(user: user) nameLabel.text = viewModel.name birthdayLabel.text = viewModel.birthdayString salaryLabel.text = viewModel.salary piLabel.text = viewModel.millionthDigitOfPi } }

asynchronously viewModel.getFacebookFriends { friends in self.friendCountLabel.text = "\(friends.count)" }

class ViewModel { func getFacebookFriends(completion: [User] -> Void) { let client = APIClient() client.getFacebookFriends(for: user) { friends in DispatchQueue.main.async { completion(friends) } } } }

> KVO > Delegate > Notification > Closure

BINDING class Binding { var value: T { didSet { listener?(value) } } private var listener: ((T) -> Void)? init(value: T) { self.value = value } func bind(_ closure: @escaping (T) -> Void) { closure(value) listener = closure } }

class ViewModel { let friends = Binding<[User]>(value: []) init() { getFacebookFriends { friends.value = $0 } } func getFacebookFriends(completion: ([User]) -> Void) { // Do the work } }

override func viewDidLoad() { super.viewDidLoad() viewModel.friends.bind { friends in self.friendsCountLabel.text = "\(friends.count)" } }

RXSWIFT https://github.com/ReactiveX/RxSwift

OBSERVABLE Source http://rxmarbles.com/#filter

class ViewModel { let friends: Observable<[User]> init() { let client = APIClient() friends = Observable<[User]>.create({ subscriber in client.getFacebookFriends(completion: { friends in subscriber.onNext(friends) subscriber.onCompleted() }) return Disposables.create() }) } }

override func viewDidLoad() { super.viewDidLoad() viewModel.friends.subscribe(onNext: { friends in self.friendsCountLabel.text = "\(friends.count)" }) }

let facebookFriends: Observable<[User]> // network request let twitterFriends: Observable<[User]> // network request let totalFriends: Observable<[User]> = Observable.combineLatest([facebookFriends, twitterFriends]) { friends in return Array(friends.joined()) }

VIEWCONTROLLER AND VIEW class BaseViewController: UIViewController { lazy var root: V = V() override func viewDidLoad() { super.viewDidLoad() view.addSubview(root) } }

class ProfileView: UIView { // Construct subviews and do Auto Layout here } class ProfileViewController: BaseViewController { // Handle actions from view } let profileVC = ProfileViewController() navigationController.pushViewController(profileVC, animated: true)

INPUT OUTPUT class ViewModel { class Input { let fetch = PublishSubject<()>() } class Output { let friends: Driver<[User]> } let apiClient: APIClient let input: Input let output: Output init(apiClient: APIClient) { self.apiClient = apiClient // Connect input and output } }

class ProfileViewController: BaseViewController { let viewModel: ProfileViewModelType init(viewModel: ProfileViewModelType) { self.viewModel = viewModel } override func viewDidLoad() { super.viewDidLoad() // Input viewModel.input.fetch.onNext(()) // Output viewModel.output.friends.subscribe(onNext: { friends in self.friendsCountLabel.text = "\(friends.count)" }) } }

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