iOSCon

Introduction to Functional Reactive

Programming

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Functional Reactive Programming

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Streams

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Stream

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Arrayslet values = [1, 2, 3, 4]let doubledValues = values.map { $0 * 2 }let higherThanTwo = values.filter { $0 > 2 }let sum = values.reduce(0, +)

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Filter

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Combine Latest

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Chaining manipulations let names = nameField.reactive.text

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Chaining manipulations names.filter { $0.characters.count >= 3}

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Chaining manipulations names.filter { $0.characters.count >= 3} .map { return "Dear" + $0 }

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Chaining manipulations let prefixedNames = names.filter { $0.characters.count >= 3} .map { return "Dear" + $0 }

let combined = combineLatest(prefixedNames, surnames)

combined.observeValues { prefixedNames, surname in print("Form input is \(prefixedNames) \(surname)") }

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www.rxmarbles.com

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ReactiveSwift

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Events flow

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Non-Terminating• Next

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Terminating

• Completed

• Failed

• Interrupted (Reactive Cocoa)

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This screen is a signal

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Represents events over time

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Observe

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If you don't observe, it's gone

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Observingpresentation.observeValues { idea in remember(idea: idea)}

presentation.observeCompleted { print("Time for a break")}

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Signal producer

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Represents a tasks

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Does not start it's work if not asked

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Producingpresenter.startWithSignal { (signal, _) in signal.observeValues { idea in print(idea) }

signal.observeCompleted { print("Time for a break") }}

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Hot vs Cold

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Signal SignalProducer

presentation.observeValues presentation.startWithValues

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Signal SignalProducer

presentation.observeValues presentation.startWithValues

emits values all the time waits for your request

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Properties

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Bindings

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Binding examplelet (slides, _) = Signal<Slide, NoError>.pipe()

label.reactive.text <~ slides.map { return "Slide: \($0.number)" }

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Memory Management

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Disposables

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Free your memorylet disposable = signal.observeValues { value in ...}

deinit { disposable.dispose()}

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FUNctional reactive programming

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