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@mluisbrown
Last active May 19, 2024 10:47
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An RxSwift to ReactiveSwift cheatsheet

RxSwift to ReactiveSwift Cheatsheet

This is a Cheatsheet for RxSwift developers migrating to projects using ReactiveSwift.

Inspired by the RxSwift to Combine cheatsheet

Basics

RxSwift ReactiveSwift
Deployment Target iOS 8.0+ iOS 8.0+
Platforms supported iOS, macOS, tvOS, watchOS, Linux iOS, macOS, tvOS, watchOS, Linux.
Spec Reactive Extensions (ReactiveX) FRP
Framework Consumption Third-party Third-party
Maintained by Open-Source / Community Open-Source / Community
UI Bindings RxCocoa. ReactiveCocoa

Core Components

RxSwift ReactiveSwift Notes
AnyObserver Signal.Observer In practise, since there are no different Observer types, the AnyObserver concept is redundant in ReactiveSwift
BehaviorRelay Property / MutableProperty Since MutableProperty can never have errors, we don't need a Relay specific version.
BehaviorSubject Property / MutableProperty
Completable Signal / SignalProducer A Signal or SignalProducer where Value == Never can only complete or emit an error event
CompositeDisposable CompositeDisposable
ConnectableObservableType
Disposable Disposable Note: in ReactiveSwift you rarely have to keep hold of Disposables or manage their lifetime manually, it's mostly automatic.
DisposeBag CompositeDisposable
Driver
Maybe Trivial to create using take(first: 1)
Observable Signal / SignalProducer Signal is a "hot" observable, and SignalProducer is a "cold" observable that will only emit values once a subscription is started
Observer Signal.Observer
PublishRelay Could be recreated easily in ReactiveSwift using the flatMapError operator on a Signal.pipe()
PublishSubject Signal.pipe() There is no Subject type, but Signal.pipe() returns a tuple of (output: Signal, input: Signal.Observer) which you use to both observe and send values
ReplaySubject Can be created using the replayLazily(upTo:) operator
ScheduledDisposable
SchedulerType Scheduler
SerialDisposable SerialDisposable
Signal NOTE: not to be confused with ReactiveSwift Signal which is completely different
Single Could easily be created as an initializer for SignalProducer
SubjectType Signal.pipe() There is no Subject type, but Signal.pipe() returns a tuple of (output: Signal, input: Signal.Observer) which you use to both observe and send values
TestScheduler TestScheduler

Operators

RxSwift ReactiveSwift Notes
amb() flatten(.race)
asObservable() Not required in ReactiveSwift, although Property.producer and Property.signal are similar
asObserver()
bind(to:) <~ operator (BindingTargets)
buffer (it used to exist, but was removed)
catchError flatMapError
catchErrorJustReturn Easy to create as flatMapError { _ in SignalProducer<Value, Never> (value: value) }
combineLatest combineLatest
compactMap compactMap
concat concat / prefix
concatMap
create SignalProducer.init { }
debounce debounce
debug logEvents
deferred Trivial to create
delay delay
delaySubscription
dematerialize dematerialize
distinctUntilChanged skipRepeats
do on
elementAt
empty SignalProducer.empty
enumerated
error SignalProducer.init(error:)
filter filter
first take(first:) (see also take(last:) )
flatMap flatMap(.merge)
flatMapFirst flatMap(.throttle)
flatMapLatest flatMap(.latest)
from(optional:) Easy to create using .init(.value: Value?).skipNil()
groupBy
ifEmpty(default:)
ifEmpty(switchTo:)
ignoreElements Easy to create
interval
just SignalProducer.init(value:)
map map
materialize materialize
merge merge
merge(maxConcurrent:)
multicast replayLazily(upTo:)
never SignalProducer.never
observeOn observe(on:)
of SignalProducer.init(_ values:)
publish
range
reduce reduce
refCount Not meaningful in ReactiveSwift
repeatElement repeat
retry, retry(3) retry(upTo:)
retryWhen
sample sample(on:), sample(with:)
scan scan
share replayLazily(upTo:)
skip skip(first:)
skipUntil skip(until:)
skipWhile skip(while:)
startWith prefix
subscribe startWithValues / observeValues
subscribeOn start(on:) / observe(on:)
takeLast take(last:)
takeUntil take(until:)
throttle throttle
timeout timeout
timer SignalProducer.timer
toArray collect
window
withLatestFrom combineLatest
zip zip
@iamyogish
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Hello 👋

Thanks for this gist :) I always open this whenever I am dealing with ReactiveSwift code at work.

Today I just noticed that, in the operators section table, the second column is incorrectly named as Combine could you please update it? :)

Since it's a gist, I can't update it otherwise I'd have updated it.

Thank you!

@mluisbrown
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Hi @iamyogish,
Thanks for the correction! I've fixed it now 👍

@iamyogish
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Thank you @mluisbrown.

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