Reactive Life

Transcript

1. REACTIVE LIFE Petro Korienev iOS Team Lead @ Sigma Software
2. #cocoaheadsukraine Petro Korienev Reactive Life DISCLAIMER Many of you may be sceptic about ReactiveCocoa, so my goal for today will be to show that it’s not that bad. I don’t pretend to be expert in functional, reactive or functional reactive programming, but I’d like to show you how it can solve problems. At least for me
3. #cocoaheadsukraine Petro Korienev Reactive Life THIS IS MARS HE’S SCEPTIC ABOUT REACTIVECOCOA
4. #cocoaheadsukraine Petro Korienev Reactive Life CONTENTS •What’s RAC •RAC Objective-C •RAC 5 •Examples
5. #cocoaheadsukraine Petro Korienev Reactive Life “What’s RAC?”
6. #cocoaheadsukraine Petro Korienev Reactive Life
7. #cocoaheadsukraine Petro Korienev Reactive Life Latest ObjC release is 2.5
8. #cocoaheadsukraine Petro Korienev Reactive Life Latest Swift is 5.0.1
9. #cocoaheadsukraine Petro Korienev Reactive Life THE MOST IMPORTANT DEFINITION IS SIGNAL •Sends value/(s) to its observers •Sends completions and errors •Can participate in expressions, resulting in new signals or producing state •Signal is universal abstraction
10. #cocoaheadsukraine Petro Korienev Reactive Life OBJECTIVE-C: ReactiveCocoa 2.5 highlights
11. #cocoaheadsukraine Petro Korienev Reactive Life Rough class diagram
12. #cocoaheadsukraine Petro Korienev Reactive Life RACSTREAM •Abstract class representing any stream of values •RACStream is a monad •RACStream’s can be combined into arbitrary functional expressions
13. #cocoaheadsukraine Petro Korienev Reactive Life RACSIGNAL: RACSTREAM •RACSignal is a derivate of RACStream that can be observable with side-effects •RACSignal is the entity that manages the concept of subscription •Subscription has it’s start and finish •There can be multiple subscriptions
14. #cocoaheadsukraine Petro Korienev Reactive Life RACSEQUENCE: RACSTREAM •RACSequence is a derivate of RACStream that converts composite type to stream •Thus RACSequence makes array, dictionary, string a monad •Thus functional additions are added to Foundation
15. #cocoaheadsukraine Petro Korienev Reactive Life And now, why it’s ReactiveCocoa ?
16. #cocoaheadsukraine Petro Korienev Reactive Life KILLER-FEATURES •Reactive KVO •UI & Foundation extensions •Rockstar macros & operations •Extensible architecture
17. #cocoaheadsukraine Petro Korienev Reactive Life NOW MARS GONNA TRY IT
18. #cocoaheadsukraine Petro Korienev Reactive Life REACTIVE KVO - (RACSignal *)rac_valuesForKeyPath:(NSString *)keyPath observer:(__weak NSObject *)observer;
19. #cocoaheadsukraine Petro Korienev Reactive Life UI & FOUNDATION EXTENSIONS - (RACSignal *)rac_signalForControlEvents: (UIControlEvents)controlEvents;
 - (RACSignal *)rac_signalForSelector:(SEL)selector fromProtocol:(Protocol *)protocol;
 
 - (RACSignal *)rac_addObserverForName:(NSString *)notificationName object:(id)object;
20. #cocoaheadsukraine Petro Korienev Reactive Life ROCKSTAR MACROS & OPERATIONS RAC(self, regBtn.enabled) = [RACSignal combineLatest: @[RACObserve(self, passwordField.text), RACObserve(self, passwordConfirmation.text)] reduce:^(NSString *password, NSString *passwordConfirmation) { return @([passwordConfirmation isEqualToString:password]); }];
21. #cocoaheadsukraine Petro Korienev Reactive Life @weakify(self);
 [[[NSNotificationCenter defaultCenter] rac_addObserverForName:UIApplicationWillResignActive Notification object:nil] subscribeNext:^(NSNotification *note) {
 @strongify(self); … }]; ROCKSTAR MACROS & OPERATIONS
22. #cocoaheadsukraine Petro Korienev Reactive Life EXTENSIBLE ARCHITECTURE •Example of filtering string https:/ /gist.github.com/soxjke/ b09175b252c597a2d468b9fbbe00cca3
23. #cocoaheadsukraine Petro Korienev Reactive Life OBJECTIVE-C DOWNSIDES •Type-unsafe subscriptions. •Easy-to-write retain cycles •Debugging complexity •Values-over-time are difficult to test •Complex expressions are often way unreadable.
 Especially without ReactiveCocoa experience
24. #cocoaheadsukraine Petro Korienev Reactive Life READABILITY - REACTIVEHELL •Example data structure to parse & solution: https:/ /gist.github.com/soxjke/ 4269e56942a0561f9adc60f9c7f3b41b
25. #cocoaheadsukraine Petro Korienev Reactive Life
26. #cocoaheadsukraine Petro Korienev Reactive Life MARS DOESN’T LIKE REACTIVECOCOA STACKTRACE
27. #cocoaheadsukraine Petro Korienev Reactive Life FEW DEBUGGING TIPS •use rac_willDeallocSignal to observe lifetimes when debugging intermittent crashes •use RACSignal (Debug) category with log methods •try breaking complex signal expressions and inject side effects on each step
28. #cocoaheadsukraine Petro Korienev Reactive Life WHAT ABOUT SWIFT?
29. #cocoaheadsukraine Petro Korienev Reactive Life SWIFT ReactiveCocoa 5
30. #cocoaheadsukraine Petro Korienev Reactive Life REACTIVE SWIFT KEY DIFFS •Compile-time type-safety •Protocol-oriented design •Hot&cold observables
31. #cocoaheadsukraine Petro Korienev Reactive Life COMPILE-TIME TYPE-SAFETY public final class Signal<Value, Error: Swift.Error> public struct SignalProducer<Value, Error: Swift.Error> public protocol ObserverProtocol { associatedtype Value associatedtype Error: Swift.Error func send(value: Value) func send(error: Error) func sendCompleted() func sendInterrupted() }
32. #cocoaheadsukraine Petro Korienev Reactive Life SIGNAL •“Hot” observable, subscription shouldn’t involve side-effects according to guidelines •Observing results in Disposable? •There’re “value”, “error”, “completed”, “interrupted” events
33. #cocoaheadsukraine Petro Korienev Reactive Life SIGNALPRODUCER •“Cold” observable, starting it may produce a signal, indicating status of some underlying operation. •Observing results in Disposable, used to terminate observation & stop sending values
34. #cocoaheadsukraine Petro Korienev Reactive Life MORE USEFUL CLASSES •MutableProperty, DynamicProperty •UIScheduler •Action •…
35. #cocoaheadsukraine Petro Korienev Reactive Life MARS IS TIRED
36. #cocoaheadsukraine Petro Korienev Reactive Life EXAMPLE 1. PLACES SEARCH •https:/ /github.com/soxjke/ReactiveLife
37. #cocoaheadsukraine Petro Korienev Reactive Life WHAT’S STILL UNCOVERED •In-depth look into operators •Action •Building framework for tests •Building your own reactive UI framework •UIScheduler •Action •…
38. #cocoaheadsukraine Petro Korienev Reactive Life You may find these slides @ https:/ /speakerdeck.com/ soxjke/reactive-life THANKS!
39. #cocoaheadsukraine Petro Korienev Reactive Life ME: https://twitter.com/soxjke https://github.com/soxjke https://www.facebook.com/soxjke https://stackoverflow.com/users/2392973