iOS Reactive Cocoa Pipeline

Рак мозга или мозг рака
Раком можно все

•Application Layer
•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Persistence
Notiﬁcations
Runtime

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
NSNotiﬁcation
LocationUpdate

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Networking
Networking policies

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
HTTP.Request
HTTP.Response
HTTP.Error

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
API Request
Persistence Request
Application Service wrapper

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Update request
Value Object
Service Object

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Business logic
Logic state

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Model Object

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Application State
Presentation Logic

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Bindings
Presentables

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Presentation
UI State

•Transport Layer
•Service Layer
•Model Layer
•ViewModel Layer
•View Layer
Presenters
UIObjects
Foundation Types

RAC
• Signal
• SignalProducer
• Action
• Property
• Result

RAC
• Signal
• SignalProducer
• Action
• Property
• Result
• Pipeline
• Future Task
• Future Builder
• Reactive State
• Enum<Value | Error>

RAC
• Signal
• SignalProducer
• Action
• Property
• Result
• NSNotiﬁcationCenter
• startWithCompletion:
• startWithInput:Completions
• value + KVO
• completions(result, error)

RAC + Transforms
• Signal -> Signal - Operator
• Signal.map(transform)
• Signal.retry(3)
• Signal -> Signal -> Signal - pipeline
- retry(map(signal, transform), 3)
✓ signal.map(transform).retry(3)

Transport Layer + RAC
let requestAction = Action<URLRequest, URLResponse, Error> { .../*future task*/ }
let http = Action<Request, Response, Error> { request in
return Result<Request, Error>(value: request)
.flatMap(serialize) //Result<JSON, Error>
.flatMap(requestBuilder(forConfiguration: configuration)) //Result<URLRequest, Error>
.map(SignalProducer.init) //SignalProducer<URLRequest, Error>
.flatMap(.Latest, transform: requestAction.apply) //SignalProducer<URLResponse, Error>
.attemptMap(deserialize) //SignalProducer<Response Error
}
Заметьте - эта штука вполне может
быть общей вне зависимости от
входных и выходных данных засчет
generic

Build Your Own RAC
extension SignalType {
/// Returns a signal that will yield an array of values when `self` completes.
@warn_unused_result(message="Did you forget to call `observe` on the signal?")
public func collect() -> Signal<[Value], Error> {
return self
.reduce(CollectState()) { $0.append($1) }
.map { $0.values }
}
}

Transport Layer + RAC
let httpWithPolicy = Action<Request, Response, Error> { request in
http.apply(request)
.retry(3)
.suspendOn(enterBackgroundSignal: background, enterForeground: foreground)
}

Service Layer + RAC
let service = Action<Number, Image, Error> { number in
let image = cacheService.inquire
.apply(number)
.concat { xkcdImageHTTP.apply(number) }
let description = xkcdDescriptionHTTP.apply(number)
return combineLatest(image, description).map { ImageWithDescription(image: $0, description: $1) }
}

Model Layer + RAC
struct State {
let number: Int
let value: AnyProperty<ImageWithDescription?>
init(number: Int) {
self.number = number
self.value = AnyProperty(value: nil, producer: service.apply(number))
}
}
let state = MutableProperty(State(number: 100))
let increment = { number.value = State(number: number.value.number + 1) }
let exposedState = AnyProperty(state)

VM Layer + RAC
let image = model.exposedState
.flatMap { $0.value.image }
.map { $0 ?? imagePlaceholder }
let description = model.exposedState
.flatMap { $0.value.description }
.map { $0 ?? "Loading..." }
let rightButtonAction = model.increment
let present = { presenters in
presenters.rightButtonAction <~ rightButtonAction
presenters.description <~ description.producer
presenters.image <~ description.image
}

View + RAC
class View {
//{ self.imageView.image = $0 }
let image: Presenter<UIImage> = self.imageView.imagePresenter
//{ self.descriptionLabel.value = $0 }
let description: Presenter<String> = self.descriptionLabel.textPresenter
//{ self.button.clickedSignal.observe($0) }
let rightButton: Presenter<() -> ()> = self.button.clickActionPresenter
}

Beneﬁts?
• Consistency
• Observability
• Testability
• Encapsulation
• Completeness

Examples?
Popup Action
Navigation Property + Actions
UIKit Sinks + Presentables
Login Form Action + Operators

What’s next?
• RXMarbles (http://rxmarbles.com/)
• Reactive Cocoa sources - all here

iOS Reactive Cocoa Pipeline

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