Why do you need to switch from Obj-C to Swift, or let's talk about ReactiveCocoa v4

- what has been changed since ReactiveCocoa v2

- how to make CocoaTouch reactive 🚀

- a few words about MVVM architecture designed with ReactiveCocoa v4

Transcript

1. Why do you need to switch from Objective-C to Swift, or let’s talk about ReactiveCocoa v4 Malakhovskyi Vitalii iOS Developer @
2. - what has been changed since ReactiveCocoa v2 - how to make CocoaTouch reactive - a few words about MVVM architecture designed with ReactiveCocoa v4 So what we will talk about:
3. What is ReactiveCocoa ?
4. Hot and Cold
5. HOT … — .Next(Void) — .Next(Void) — .Next(Void) — … … — .Next(Void) — .Next(Void) — .Completed | COLD | — .Next(data) — Completed | | — .Error(.ConnectionLost) | S S S S
6. Objective-C & ReactiveCocoa v2.5 RACSignal type represents both hot and cold signals.
8. Events public enum Event<Value, Error: ErrorType> { case Next(Value) case Failed(Error) case Completed case Interrupted }
9. Signal<Int, NoError>
13. New events prerogatives: • strict types • generics • code highlighting • ErrorType -> NoError
14. Hot Signal
15. Cold SignalProducer
16. let signal: SignalProducer<Bool, NoError> let observer: Observer<Bool, NoError> init() { (signal, observer) = SignalProducer.buffer(3) } signal.startWithNext { value in print(value) } observer.sendNext(true) // true observer.sendNext(false) // false observer.sendNext(false) // false signal.startWithNext { value in print(value) } // true // false // false
17. Properties public protocol PropertyType { typealias Value var value: Value { get } var producer: SignalProducer<Value, NoError> { get } }
18. • MutableProperty • ConstantProperty • AnyProperty • DynamicProperty Properties can be
19. KVO vs Property
20. class Car: NSObject { dynamic var miles = 0 dynamic var name = "TAZ" }
21. class CarObserver: NSObject { private var kvoContext: UInt8 = 1 private let car: Car init(_ car: Car) { self.car = car super.init() car.addObserver(self, forKeyPath: "miles", options: NSKeyValueObservingOptions.New, context: &kvoContext) } override func observeValueForKeyPath(keyPath: String, ofObject object: AnyObject, change: [String : AnyObject], context: UnsafeMutablePointer<Void>) { if context == &kvoContext { print("Change at keyPath = \(keyPath) for \(object)") } } deinit { car.removeObserver(self, forKeyPath: "miles") } }
22. KVO in Swift • NSObject inheritance - should be Objective-C types - i.e. no structs, enums, and no generics • dynamic attribute • cumbersome method signature
23. • property <~ signal • property <~ producer • property <~ otherProperty Meet “<~”
24. Action Action<Input, Output, Error: ErrorType>
25. let enabled = MutableProperty(false) enabled <~ combineLatest(self.username.producer, self.password.producer) .map { return $0.characters.count >= 1 && $1.characters.count >= 1 } signIn = Action<Void, User, NSError>(enabledIf: enabled) { _ -> SignalProducer<User, NSError> in return self.model.authorize(self.username.value, password: self.password.value) }
26. @IBAction func onSignButtonTap(sender: UIButton) { viewModel.signIn.apply().start() } OR self.action = CocoaAction(viewModel.signIn, input: () ) loginButton.addTarget(action, action: CocoaAction.selector, forControlEvents: UIControlEvents.TouchUpInside )
27. loginButton.rac_enabled <~ viewModel.signIn.enabled.producer.takeUntil(rac_willDeallocSignalProducer()) viewModel.signIn.executing.producer .takeUntil(rac_willDeallocSignalProducer()) .startWithNext { [weak self] executing in if executing { self?.activityIndicator.startAnimating() } else { self?.activityIndicator.stopAnimating() } }
28. Reactive UI
30. func lazyAssociatedProperty<T: AnyObject>(host: AnyObject, key: UnsafePointer<Void>, factory: () -> T) -> T { return objc_getAssociatedObject(host, key) as? T ?? { let associatedProperty = factory() objc_setAssociatedObject(host, key, associatedProperty, objc_AssociationPolicy.OBJC_ASSOCIATION_RETAIN) return associatedProperty }() } func lazyMutableProperty<T>(host: AnyObject, key: UnsafePointer<Void>, setter: T -> (), getter: () -> T) -> MutableProperty<T> { return lazyAssociatedProperty(host, key: key) { let property = MutableProperty<T>(getter()) property.producer.startWithNext { newValue in setter(newValue) } return property } } https://github.com/vmalakhovskiy/RACExtensions
31. struct AssociationKey { static var text: UInt8 = 0 static var textColor: UInt8 = 1 } extension UILabel { public var rac_text: MutableProperty<String> { return lazyMutableProperty(self, key: &AssociationKey.text, setter: { self.text = $0 }, getter: { self.text ?? "" }) } public var rac_textColor: MutableProperty<UIColor> { return lazyMutableProperty(self, key: &AssociationKey.textColor, setter: { self.textColor = $0 }, getter: { self.textColor }) } }
32. extension UISearchBar: UISearchBarDelegate { public var rac_text: MutableProperty<String> { return lazyAssociatedProperty(self, key: &AssociationKey.text) { self.delegate = self self.rac_signalForSelector(Selector("searchBar:textDidChange:"), fromProtocol: UISearchBarDelegate.self) .toSignalProducer() .startWithNext({ [weak self] _ in self?.changed() }) let property = MutableProperty<String>(self.text ?? "") property.producer.startWithNext { newValue in self.text = newValue } return property } } func changed() { rac_text.value = self.text ?? "" } }
33. MVVM - DEMO
35. Model ViewModel View
36. Model func signIn(login: String, password: String) -> SignalProducer<User, NSError> ViewModel var username: MutableProperty<String> { get } var password: MutableProperty<String> { get } var signIn: Action<Void, User, NSError> { get } View @IBOutlet weak var userNameField: TextFieldWithInset @IBOutlet weak var passwordField: TextFieldWithInset @IBOutlet weak var loginButton: UIButton @IBOutlet weak var activityIndicator: UIActivityIndicatorView
37. Model public protocol LoginModel { func signIn(login: String, password: String) -> SignalProducer<User, NSError> } public class LoginModelImpl: LoginModel { let loginManager: LoginManager public init(loginManager: LoginManager) { self.loginManager = loginManager } public func signIn(login: String, password: String) -> SignalProducer<User, NSError> { return loginManager.signIn(login, password: password) } }
38. ViewModel public protocol LoginViewModel { var username: MutableProperty<String> { get } var password: MutableProperty<String> { get } var signIn: Action<Void, User, NSError>! { get } } public class LoginViewModelImpl: LoginViewModel { private let model: LoginModel public let username: MutableProperty<String> = MutableProperty("") public let password: MutableProperty<String> = MutableProperty("") public var signIn: Action<Void, User, NSError>! public init(model: LoginModel, initialUsername: String, lastLoginError: NSError?) { self.model = model let enabledSignal = MutableProperty(false) enabledSignal <~ combineLatest(self.username.producer, self.password.producer) .map { return $0.characters.count >= 1 && $1.characters.count >= 1 } signIn = Action<Void, User, NSError>(enabledIf: enabledSignal) { _ -> SignalProducer<User, NSError> in return self.model.signIn(self.username.value, password: self.password.value) } } }
39. View private func setupBindings() { viewModel.username <~ userNameField.rac_text.producer.takeUntil(rac_willDeallocSignalProducer()) viewModel.password <~ passwordField.rac_text.producer.takeUntil(rac_willDeallocSignalProducer()) loginButton.rac_enabled <~ viewModel.signIn.enabled.producer.takeUntil(rac_willDeallocSignalProducer()) viewModel..executing.producer .takeUntil(rac_willDeallocSignalProducer()) .startWithNext { [weak self] executing in if executing { self?.activityIndicator.startAnimating() } else { self?.activityIndicator.stopAnimating() } } loginButton.addTarget(action, action: CocoaAction.selector, forControlEvents: UIControlEvents.TouchUpInside) viewModel.signIn.values.observeNext { [weak self] user in } viewModel.signIn.errors.observeNext { [weak self] error in } }
40. To sum up: • pure Swift implementation • updated events • separating hot and cold signals • new property feature • type safety • much nicer syntax
41. Щастя! Здоровля!
42. Contact me: purpleshirted crimsongf Vitaliy Malakhovskiy
43. https://spin.atomicobject.com/2015/10/26/ reactivecocoa-4-differences/ https://github.com/ReactiveCocoa/ReactiveCocoa/tree/ master/Documentation http://nomothetis.svbtle.com/an-introduction-to- reactivecocoa http://blog.scottlogic.com/2015/05/15/mvvm-reactive- cocoa-3.html http://blog.scottlogic.com/2015/02/11/swift-kvo- alternatives.html
44. https://github.com/vmalakhovskiy/RACExtensions