Conquering ReactiveSwift

I used these slides in my talk at iOSDevUK 2019.
This talk walks you through different primitives of ReactiveSwift.

Transcript

1. > < next previous CONQUERING REACTIVESWIFT Susmita Horrow
2. > < next previous UILABEL UITEXTFIELD
3. > < next previous label.text = textfield.text
4. > < next previous t1 “h” t2 “he” t3 “hel” t4 “hell” t5 “hello” label.text = textfield.text label.text = textfield.text label.text = textfield.text label.text = textfield.text label.text = textfield.text IMPERATIVE
5. > < next previous t1 “h” t2 “he” t3 “hel” t4 “hell” t5 “hello” REACTIVE label.reactive.text <~ textField.reactive.continuousTextValues.skipNil()
6. > < next previous Source Consumer Scope Operators Observer Mutable Property Side Effects Binding Transform Combine Flatten Lifetime Disposable Property Event Signal Signal Producer Action PRIMITIVES
7. > < next previous Enable button when a textfield has non empty text
8. > < next previous let observer: Observer<Bool, Never> = Observer(value: { value in button.isEnabled = value }) textField.reactive.continuousTextValues.skipNil() let disposable = .map { text in text.characters.count > 0 } .observe(observer) disposable?.dispose() SOURCE CONSUMER SCOPE OPERATOR
9. > < next previous OBSERVER SIGNAL EVENT DISPOSABLE SIGNALPRODUCER BINDING MUTABLEPROPERTY LIFETIME PROPERTY ACTION OPERATORS MILESTONE
10. > < next previous EVENT The basic unit ‣ Completed ‣ Failed ‣ Interrupted ‣ Value
11. > < next previous SIGNAL A unidirectional stream of events 6 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1
12. > < next previous OBSERVER The responder to the stream of events Encapsulates the work to be performed in response to the events emitted
13. > < next previous let observer = Signal<Int, Never>.Observer { (event) in switch event { case let .value(v): print("value = \(v)”) case let .failed(error): print("error = \(error)”) case .completed: print(“completed") case .interrupted: print("interrupted") } }
14. > < next previous Print a message of time elapsed on every 5 seconds interval for 50 seconds
15. > < next previous let (output, input) = Signal<Int, Never>.pipe() Observer<Int, Never> INPUT Signal<Int, Never> OUTPUT
16. > < next previous let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { } input.send(value: timeElapsed) DispatchQueue.main.asyncAfter(deadline: .now() + Double(timeElapsed)) { } let timeElapsed = index * 5
17. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer
18. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } )
19. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } ) let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { let timeElapsed = index * 5 DispatchQueue.main.asyncAfter( deadline: .now() + Double(timeElapsed)) { input.send(value: timeElapsed) } }
20. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } ) let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { let timeElapsed = index * 5 DispatchQueue.main.asyncAfter( deadline: .now() + Double(timeElapsed)) { input.send(value: timeElapsed) } } output.observe(signalObserver)
21. > < next previous OBSERVER SIGNAL EVENT DISPOSABLE SIGNALPRODUCER BINDING MUTABLEPROPERTY LIFETIME PROPERTY ACTION OPERATORS MILESTONE
22. > < next previous SIGNALPRODUCER A deferred and repeatable work that creates a stream of values 6 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 SIGNALPRODUCER START START START
23. > < next previous Print a message of time elapsed on every 5 seconds interval for 50 seconds
24. > < next previous Print a message of time elapsed on every 5 seconds interval for 50 seconds which starts on a button tap
25. > < next previous let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in } for i in 0..<10 { } if i == 9 { //Mark completion on 9th iteration observer.sendCompleted() } observer.send(value: timeElapsed) } DispatchQueue.main.asyncAfter(deadline: .now() + Double(timeElapsed)) { let timeElapsed = index * 5
26. > < next previous ‣ Start the signalProducer ‣ Create the signalProducer ‣ Create the observer
27. > < next previous ‣ Start the signalProducer ‣ Create the signalProducer ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } )
28. > < next previous ‣ Start the signalProducer ‣ Create the signalProducer ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } ) let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in for i in 0..<10 { let timeElapsed = index * 5 DispatchQueue.main.asyncAfter( deadline: .now() + Double(timeElapsed)) { observer.send(value: timeElapsed) if i == 9 { observer.sendCompleted() } } } }
29. > < next previous ‣ Start the signalProducer ‣ Create the signalProducer ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } ) let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in for i in 0..<10 { let timeElapsed = index * 5 DispatchQueue.main.asyncAfter( deadline: .now() + Double(timeElapsed)) { observer.send(value: i) if i == 9 { observer.sendCompleted() } } } } signalProducer.start(signalObserver)
30. > < next previous DISPOSABLE & LIFETIME Represents something that can be “disposed”, usually associated with freeing resources or canceling work. let disposable: Disposable? = signal.observe(signalObserver) disposable.dispose()
31. > < next previous DISPOSABLE & LIFETIME Represents something that can be “disposed”, usually associated with freeing resources or canceling work. disposable.dispose() let disposable: Disposable? = signalProducer.start(signalObserver)
32. > < next previous let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in } for i in 0..<10 { } if i == 9 { observer.sendCompleted() } observer.send(value: timeElapsed) } DispatchQueue.main.asyncAfter(deadline: .now() + Double(timeElapsed)) { let timeElapsed = index * 5
33. > < next previous let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in } for i in 0..<10 { } if i == 9 { observer.sendCompleted() } observer.send(value: timeElapsed) } DispatchQueue.main.asyncAfter(deadline: .now() + Double(timeElapsed)) { let timeElapsed = index * 5 Lifetime of the produced signal
34. > < next previous let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in for i in 0..<10 { let timeElapsed = index * 5 DispatchQueue.main.asyncAfter(deadline: .now() + Double(timeElapsed)) { guard !lifetime.hasEnded else { observer.sendInterrupted() return } observer.send(value: timeElapsed) if i == 9 { observer.sendCompleted() } } } }
35. > < next previous SIGNAL SIGNALPRODUCER ‣ Like video stream in TV ‣ Like on demand stream in Youtube ‣ Sequence of stream is same for all observer ‣ Sequence of stream is different for different observer ‣ Observer cannot interrupt the stream ‣ Observer can interrupt the stream ‣ Can represent event streams that are already “in progress,” such as notifications, user input ‣ Can represent operations or tasks which need to be started such as network requests
36. > < next previous OBSERVER SIGNAL EVENT DISPOSABLE SIGNALPRODUCER BINDING MUTABLEPROPERTY LIFETIME PROPERTY ACTION OPERATORS MILESTONE LIFETIME
37. > < next previous PROPERTY An observable box that always holds a value
38. > < next previous PROPERTY 6 5 4 3 2 1 .signal .producer 6 5 4 3 2 1 START .value 1
39. > < next previous let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in for i in 0..<10 { DispatchQueue.main.asyncAfter(deadline: .now() + 5.0 * Double(i)) { guard !lifetime.hasEnded else { observer.sendInterrupted() return } observer.send(value: timeElapsed) if i == 9 { observer.sendCompleted() } } } }
40. > < next previous let property = Property(initial: 0, then: signalProducer) property.producer.startWithValues { value in print("[Observing SignalProducer] Time elapsed = \(value)") } property.signal.observeValues { value in print("[Observing Signal] Time elapsed = \(value)") }
41. > < next previous MUTABLEPROPERTY An observable and mutable box that always holds a value let mutableProperty = MutableProperty(1) mutableProperty.value = 3
42. > < next previous OBSERVER SIGNAL EVENT DISPOSABLE SIGNALPRODUCER BINDING MUTABLEPROPERTY LIFETIME PROPERTY ACTION OPERATORS MILESTONE
43. > < next previous ACTION A serialized deferred and repeatable work with a preset action. ‣ Deferred ‣ Repeatable ‣ Mutually exclusive ‣ Varying input Like SignalProducer Unlike SignalProducer
44. > < next previous Print a message of time elapsed on every 5 seconds interval for 50 seconds which starts on a button tap
45. > < next previous Print a message of time elapsed on every N seconds interval for N * 10 seconds which starts on a button tap
46. > < next previous DispatchQueue.main.asyncAfter(deadline: .now() * Double(timeElapsed)) { guard !lifetime.hasEnded else { observer.sendInterrupted() return } observer.send(value: timeElapsed) if i == 9 { observer.sendCompleted() } } let signalProducer: SignalProducer<Int, Never> = SignalProducer { (observer, lifetime) in } for i in 0..<10 { } let timeElapsed = index * 5
47. > < next previous DispatchQueue.main.asyncAfter(deadline: .now() * Double(timeElapsed)) { guard !lifetime.hasEnded else { observer.sendInterrupted() return } observer.send(value: timeElapsed) if i == 9 { observer.sendCompleted() } } let signalProducerGenerator: (Int) -> SignalProducer<Int, NoError> = { timeInterval in return SignalProducer { (observer, lifetime) } for i in 0..<10 { } let timeElapsed = index * timeInterval
48. > < next previous DispatchQueue.main.asyncAfter(deadline: .now() * Double(timeElapsed)) { guard !lifetime.hasEnded else { observer.sendInterrupted() return } observer.send(value: timeElapsed) if i == 9 { observer.sendCompleted() } } let signalProducerGenerator: (Int) -> SignalProducer<Int, NoError> = { timeInterval in return SignalProducer { (observer, lifetime) } for i in 0..<10 { } let timeElapsed = index * timeInterval
49. > < next previous let signalProducer1 = signalProducerGenerator(1) let signalProducer2 = signalProducerGenerator(2) signalProducer1.startWithValues { value in print("value from signalProducer1 = \(value)") } signalProducer2.startWithValues { value in print("value from signalProducer2 = \(value)") }
50. > < next previous Easy Right? Mutually Exclusive?
51. > < START 6 5 4 3 2 1 6 5 4 3 2 1 6 5 4 3 2 1 SIGNALPRODUCER START START APPLY ACTION next previous
52. > < next previous ACTION ‣ values Signal<Output, Never> ‣ errors Signal<Error, Never> ‣ isExecuting Property<Bool> ‣ isEnabled Property<Bool>
53. > < next previous public final class Action<Input, Output, Error: Swift.Error> {} ACTION Type of input Type of values emitted Type of error emitted
54. > < next previous ‣ Apply the action ‣ Create the observer ‣ Create the action
55. > < next previous ‣ Apply the action ‣ Create the observer ‣ Create the action let action = Action<(Int), Int, Never> (execute: signalProducerGenerator)
56. > < next previous ‣ Apply the action ‣ Create the observer ‣ Create the action let action = Action<(Int), Int, Never> (execute: signalProducerGenerator) action.values.observeCompleted { print("Action completed") } action.values.observeValues { value in print("Time elapsed = \(value)") }
57. > < next previous ‣ Apply the action ‣ Create the observer ‣ Create the action let action = Action<(Int), Int, Never> (execute: signalProducerGenerator) action.values.observeCompleted { print("Action completed") } action.values.observeValues { value in print("Time elapsed = \(value)") } action.apply(1).start() action.apply(2).start() DispatchQueue.main.asyncAfter(deadline: .now() + 12.0){ action.apply(3).start() }
58. > < next previous OBSERVER SIGNAL EVENT DISPOSABLE SIGNALPRODUCER BINDING MUTABLEPROPERTY LIFETIME PROPERTY ACTION OPERATORS MILESTONE LIFETIME
59. > < next previous BINDING Modelling behaviour in response to state change label.reactive.text <~ textField.reactive.continuousTextValues.skipNil()
60. > < next previous BindingTargetProvider <~ BindingSource MutableProperty Signal SignalProducer Property BINDING MutableProperty
61. > < next previous BindingTargetProvider <~ BindingSource BINDING let mutableProperty = MutableProperty(1) mutableProperty <~ signal
62. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } ) let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { DispatchQueue.main.asyncAfter( deadline: .now() + 5.0 * Double(i)) { input.send(value: timeElapsed) } } output.observe(signalObserver)
63. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let signalObserver = Observer<Int, Never> ( value: { value in print("Time elapsed = \(value)") }, completed: { print("completed") }, interrupted: { print("interrupted") } ) let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { DispatchQueue.main.asyncAfter( deadline: .now() + 5.0 * Double(i)) { input.send(value: timeElapsed) } } output.observe(signalObserver)
64. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { DispatchQueue.main.asyncAfter( deadline: .now() + 5.0 * Double(i)) { input.send(value: timeElapsed) } } output.observe(signalObserver) Create the BindingTarget let signalObserver = BindingTarget<Int>( lifetime: self.reactive.lifetime) { value in print("Time elapsed = \(value)") }
65. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { DispatchQueue.main.asyncAfter( deadline: .now() + 5.0 * Double(i)) { input.send(value: timeElapsed) } } output.observe(signalObserver) Create the BindingTarget let signalObserver = BindingTarget<Int>( lifetime: self.reactive.lifetime) { value in print("Time elapsed = \(value)") }
66. > < next previous ‣ Observe the signal ‣ Create the signal ‣ Create the observer let (output, input) = Signal<Int, Never>.pipe() for i in 0..<10 { DispatchQueue.main.asyncAfter( deadline: .now() + 5.0 * Double(i)) { input.send(value: timeElapsed) } } signalObserver <~ output Create the BindingTarget let signalObserver = BindingTarget<Int>( lifetime: self.reactive.lifetime) { value in print("Time elapsed = \(value)") } Bind the signal
67. > < next previous OBSERVER SIGNAL EVENT DISPOSABLE SIGNALPRODUCER BINDING MUTABLEPROPERTY LIFETIME PROPERTY ACTION OPERATORS MILESTONE LIFETIME
68. > < next previous Side Effects observe on Transform filterMap lazyMap mapError map filter Aggregate collect scan reduce Limit skip take skipRepeats uniqueValues Binding <~ skipNil debounce throttle delay or and negate Logical OPERATORS
69. > < next previous Side Effects observe on Transform filterMap lazyMap mapError map filter Aggregate collect scan reduce Limit skip take skipRepeats uniqueValues Binding <~ skipNil debounce throttle delay or and negate Logical OPERATORS
70. > < next previous Combine Flatten combineLatest combinePrevious zip merge concat latest flatMap Signal Producer then first retry repeat single last wait replayLazily Misc. materialize dematerialize sample timeout attempt attemptMap promoteError OPERATORS
71. > < next previous hsusmita/conquering-reactive-swift @SusmitaHorrow @hsusmita
72. Thank You > < next previous