RxSwift 와 Combine

원문 : https://medium.com/gett-engineering/rxswift-to-apples-combine-cheat-sheet-e9ce32b14c5b

Basics

	RxSwift	Combine
Deployment Target	iOS 8.0+	iOS 13.0+
Platforms supported	iOS, macOS, tvOS, watchOS, Linux	iOS, macOS, tvOS, watchOS, UIKit for Mac
Spec	Reactive Extensions (ReactiveX)	Reactive Streams (+ adjustments)
Framework Consumption	Third-party	First-party (built-in)
Maintained by	Open-Source / Community	Apple
UI Bindings	RxCocoa	SwiftUI

 

Core Components

RxSwift	Combine	Note
AnyObserver	AnySubscriber
BehaviorRelay	❌	Simple wrapper around BehaviorSubject, could be easily recreated in Combine
BehaviorSubject	CurrentValueSubject	This seems to be the type that holds @State under the hood
Completable	❌
CompositeDisposable	❌
ConnectableObservableType	ConnectablePublisher
Disposable	Cancellable
DisposeBag	A collection of AnyCancellables	Call anyCancellable.store(in: collection), where collection can be an array, a set, or any other RangeReplaceableCollection
Driver	BindableObject (SwiftUI)	Both guarantee no failure, but Driver guarantees delivery on Main Thread. In Combine, SwiftUI recreates the entire view hierarachy on the Main Thread, instead.
Maybe	Publishers.Optional
Observable	Publisher
Observer	Subscriber
PublishRelay	❌	Simple wrapper around PublishSubject, could be easily recreated in Combine
PublishSubject	PassthroughSubject
ReplaySubject	❌
ScheduledDisposable	❌
SchedulerType	Scheduler
SerialDisposable	❌
Signal	❌
Single	Future	They're only similar in the sense of single emission, but Future shares resources and executes immediately (very strange behavior)
SubjectType	Subject
TestScheduler	❌	There doesn't seem to be an existing testing scheduler for Combine code

 

Operators

RxSwift	Combine	Notes
amb()	❌
asObservable()	eraseToAnyPublisher()
asObserver()	❌
bind(to:)	`assign(to:on:)`	Assign uses a KeyPath which is really nice and useful. RxSwift needs a Binder / ObserverType to bind to.
buffer	buffer
catchError	catch
catchErrorJustReturn	replaceError(with:)
combineLatest	combineLatest, tryCombineLatest
compactMap	compactMap, tryCompactMap
concat	append, prepend
concatMap	❌
create	❌	Apple removed AnyPublisher with a closure in Xcode 11 beta 3 :-(
debounce	debounce
debug	print
deferred	Publishers.Deferred
delay	delay
delaySubscription	❌
dematerialize	❌
distinctUntilChanged	removeDuplicates, tryRemoveDuplicates
do	handleEvents
elementAt	output(at:)
empty	Publishers.Empty(completeImmediately: true)
enumerated	❌
error	Publishers.Fail
filter	filter, tryFilter
first	first, tryFirst
flatMap	flatMap
flatMapFirst	❌
flatMapLatest	switchToLatest
from	❌
groupBy	❌
ifEmpty(default:)	replaceEmpty(with:)
ifEmpty(switchTo:)	❌	Could be achieved with composition - replaceEmpty(with: publisher).switchToLatest()
ignoreElements	ignoreOutput
interval	❌
just	Just
map	map, tryMap
materialize	❌
merge	merge, tryMerge
merge(maxConcurrent:)	flatMap(maxPublishers:)
multicast	multicast
never	Publishers.Empty(completeImmediately: false)
observeOn	receive(on:)
of	Sequence.publisher	`publisher` property on any `Sequence` or you can use `Publishers.Sequence(sequence:)` directly
publish	makeConnectable
range	❌
reduce	reduce, tryReduce
refCount	autoconnect
repeatElement	❌
retry, retry(3)	retry, retry(3)
retryWhen	❌
sample	❌
scan	scan, tryScan
share	share	There’s no replay or scope in Combine. Could be “faked” with multicast.
skip(3)	dropFirst(3)
skipUntil	drop(untilOutputFrom:)
skipWhile	drop(while:), tryDrop(while:)
startWith	prepend
subscribe	sink
subscribeOn	subscribe(on:)	RxSwift uses Schedulers. Combine uses RunLoop, DispatchQueue, and OperationQueue.
takeLast	last
takeUntil	prefix(untilOutputFrom:)
throttle	throttle
timeout	timeout
timer	Timer.publish
toArray()	collect()
window	collect(Publishers.TimeGroupingStrategy)	Combine has a TimeGroupingStrategy.byTimeOrCount that could be used as a window.
withLatestFrom	❌
zip	zip