Reactive programming with RxSwift
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An introduction to Reactive programming in iOS with Swift
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Reactive programming with RxSwift
- 2. WHO AM I? ▸ iOS developer since 2010 ▸ Swift since day 1 ▸ Transitioning to Swift ▸ CocoaConf ▸ Wash U ▸ RayWenderlich.com ▸ lynda.com
- 3. WHO ARE YOU? ▸ iOS developer ▸ How long? ▸ Swift developer ▸ How long? ▸ Reactive programming ▸ ReactiveCocoa ▸ Reactive Extensions
- 4. WHAT IS REACTIVE PROGRAMMING?
- 5. REACTVE PROGRAMMING IS ESSENTIALLY WORKING WITH ASYNCHRONOUS DATA STREAMS @fpillet
- 6. ABOUT REACTIVE EXTENSIONS ▸ Event-driven ▸ Asynchronous ▸ Functional ▸ Common patterns ▸ Observer ▸ Iterator ▸ Cross-platform
- 7. CANONICAL EXAMPLE IMPERATIVE a = 3 b = 4 c = a + b // 7 a = 6 c // 7
- 8. CANONICAL EXAMPLE REACTIVE a = 3 b = 4 c = a + b a = 6 c // 10 // 7
- 9. TRADITIONAL VS. REACTIVE A SIMPLE EXAMPLE IN IOS
- 10. MODEL
- 11. VIEW MODEL
- 12. VIEW CONTROLLER
- 22. RX STANDARDIZES THE PATTERNS & OPERATORS USED TO DEVELOP ASYNCHRONOUS APPS IN MULTIPLE ENVIRONMENTS.
- 25. RXSWIFT OPERATORS ▸ Creating asObservable create deferred empty error toObservable interval never just of range repeatElement timer ▸ Transforming buffer flatMap flatMapFirst flatMapLatest map scan window ▸ Filtering debounce / throttle distinctUntilChanged elementAt filter sample skip take takeLast single ▸ Conditional & Boolean amb skipWhile skipUntil takeUntil takeWhile ▸ Mathematical & Aggregate concat reduce toArray ▸ Connectable multicast publish refCount replay shareReplay ▸ Combining merge startWith switchLatest combineLatest zip ▸ Error Handling catch retry retryWhen ▸ Observing delaySubscription do / doOnNext observeOn subscribe subscribeOn timeout using debug
- 26. LIFECYCLE OF AN OBSERVABLE (AKA SEQUENCE) ▸ onNext ▸ onError ▸ onComplete ▸ dispose() / DisposeBag
- 27. DO YOU HAZ TEH CODEZ ?!?
- 28. SETUP ▸ Install ThisCouldBeUsButYouPlaying ▸ bit.ly/podsPlaygrounds ▸ gem install cocoapods-playgrounds ▸ Create RxSwiftPlayground ▸ pod playgrounds RxSwift
- 29. SETUP //: Please build the scheme 'RxSwiftPlayground' first import XCPlayground XCPlaygroundPage.currentPage.needsIndefiniteExecution = true import RxSwift
- 30. SETUP //: Please build the scheme 'RxSwiftPlayground' first import XCPlayground XCPlaygroundPage.currentPage.needsIndefiniteExecution = true import RxSwift func exampleOf(description: String, action: Void -> Void) { print("n--- Example of:", description, "---") action() }
- 31. --- Example of: just --- Next(32) Completed exampleOf("just") { Observable.just(32) .subscribe { print($0) } } CREATING & SUBSCRIBING
- 32. --- Example of: just --- Next(32) Completed exampleOf("just") { Observable.just(32) .subscribe { value in print(value) } } CREATING & SUBSCRIBING
- 33. --- Example of: just --- 32 exampleOf("just") { _ = Observable.just(32).subscribeNext { print($0) } } CREATING & SUBSCRIBING
- 34. --- Example of: of --- 1 2 3 4 5 exampleOf("of") { Observable.of(1, 2, 3, 4, 5) .subscribeNext { print($0) } .dispose() } CREATING & SUBSCRIBING
- 35. --- Example of: toObservable --- 1 2 3 exampleOf("toObservable") { let disposeBag = DisposeBag() [1, 2, 3].toObservable() .subscribeNext { print($0) } .addDisposableTo(disposeBag) } CREATING & SUBSCRIBING
- 36. --- Example of: BehaviorSubject --- Next(Hello) Next(World!) exampleOf("BehaviorSubject") { let disposeBag = DisposeBag() let string = BehaviorSubject(value: "Hello") string.subscribe { print($0) } .addDisposableTo(disposeBag) string.onNext("World!") } CREATING & SUBSCRIBING
- 37. CREATING & SUBSCRIBING --- Example of: Variable --- Next(1) Next(12) Next(1234567) Completed exampleOf("Variable") { let disposeBag = DisposeBag() let number = Variable(1) number.asObservable() .subscribe { print($0) } .addDisposableTo(disposeBag) number.value = 12 number.value = 1_234_567 }
- 38. exampleOf("map") { Observable.of(1, 2, 3) .map { $0 * $0 } .subscribeNext { print($0) } .dispose() } TRANSFORMING --- Example of: map --- 1 4 9
- 39. TRANSFORMING --- Example of: Variable and map --- one twelve one million two hundred thirty-four thousand five hundred sixty-seven exampleOf("Variable and map") { let disposeBag = DisposeBag() let numberFormatter = NSNumberFormatter() numberFormatter.numberStyle = .SpellOutStyle let number = Variable(1) number.asObservable() .map { numberFormatter.stringFromNumber($0)! } .subscribeNext { print($0) } .addDisposableTo(disposeBag) number.value = 12 number.value = 1_234_567 }
- 40. TRANSFORMING --- Example of: flatMap --- Scott Lori Eric exampleOf("flatMap") { let disposeBag = DisposeBag() struct Person { var name: Variable<String> } let scott = Person(name: Variable("Scott")) let lori = Person(name: Variable("Lori")) let person = Variable(scott) person.asObservable() .flatMap { $0.name.asObservable() } .subscribeNext { print($0) } .addDisposableTo(disposeBag) person.value = lori scott.name.value = "Eric" }
- 41. TRANSFORMING --- Example of: flatMapLatest --- Scott Lori exampleOf("flatMap") { let disposeBag = DisposeBag() struct Person { var name: Variable<String> } let scott = Person(name: Variable("Scott")) let lori = Person(name: Variable("Lori")) let person = Variable(scott) person.asObservable() .flatMapLatest { $0.name.asObservable() } .subscribeNext { print($0) } .addDisposableTo(disposeBag) person.value = lori scott.name.value = "Eric" }
- 43. exampleOf("distinctUntilChanged") { let disposeBag = DisposeBag() let searchString = Variable("iOS") searchString.asObservable() .map { $0.lowercaseString } .distinctUntilChanged() .subscribeNext { print($0) } .addDisposableTo(disposeBag) searchString.value = "IOS" searchString.value = "Rx" searchString.value = "ios" } FILTERING --- Example of: distinctUntilChanged --- ios rx ios
- 44. exampleOf("combineLatest") { let disposeBag = DisposeBag() let number = PublishSubject<Int>() let string = PublishSubject<String>() Observable.combineLatest(number, string) { "($0) ($1)" } .subscribeNext { print($0) } .addDisposableTo(disposeBag) number.onNext(1) print("Nothing yet") string.on(.Next("A")) number.onNext(2) string.onNext("B") string.onNext("C") } COMBINING --- Example of: combineLatest --- Nothing yet 1 A 2 A 2 B 2 C
- 45. exampleOf("takeWhile") { [1, 2, 3, 4, 5, 6, 5, 4, 3, 2, 1].toObservable() .takeWhile { $0 < 5 } .subscribeNext { print($0) } .dispose() } CONDITIONAL --- Example of: takeWhile --- 1 2 3 4
- 46. MATHEMATICAL --- Example of: reduce --- 1024 exampleOf("reduce") { [1, 2, 4, 8, 16].toObservable() .reduce(1, accumulator: *) .subscribeNext { print($0) } .dispose() }
- 47. ERROR HANDLING --- Example of: error --- A exampleOf("error") { enum Error: ErrorType { case A } Observable<Int>.error(Error.A) .subscribeError { // Handle error print($0) } .dispose() }
- 48. RXMARBLES
- 49. RXSWIFTPLAYER
- 50. OBJECTIONS 1. Dependency 2. Complexity 3. Performance 4. Debugging 5. Help
- 51. BENEFITS 1. Write less, do more 2. Avoid mutable state errors 3. Learn once, apply everywhere 4. Mix in or go all in 5. “It reads almost like a paragraph” 6. Easy to test and heavily tested
- 52. QUESTIONS?
- 53. WANT MORE RX? ▸ github.com/ReactiveX/RxSwift ▸ reactivex.io ▸ rxmarbles.com ▸ rxswift.slack.com ▸ rx-marin.com ▸ http://as.ync.io ▸ github.com/scotteg/RxSwiftPlayer ▸ github.com/Artsy/eidolon