Swiftpack.co - Package - ReactiveX/RxSwift

Miss Electric Eel 2016 RxSwift: ReactiveX for Swift

Travis CI platforms pod Carthage compatible Swift Package Manager compatible

Rx is a generic abstraction of computation expressed through Observable<Element> interface.

This is a Swift version of Rx.

It tries to port as many concepts from the original version as possible, but some concepts were adapted for more pleasant and performant integration with iOS/macOS environment.

Cross platform documentation can be found on ReactiveX.io.

Like the original Rx, its intention is to enable easy composition of asynchronous operations and event/data streams.

KVO observing, async operations and streams are all unified under abstraction of sequence. This is the reason why Rx is so simple, elegant and powerful.

I came here because I want to ...

... understand
... install
... hack around
... interact
... compare
... understand the structure

RxSwift comprises five separate components depending on eachother in the following way:

┌──────────────┐    ┌──────────────┐
│   RxCocoa    ├────▶   RxRelay    │
└───────┬──────┘    └──────┬───────┘
        │                  │        
│             RxSwift              │
        │                  │        
┌───────┴──────┐    ┌──────┴───────┐
│    RxTest    │    │  RxBlocking  │
└──────────────┘    └──────────────┘
  • RxSwift: The core of RxSwift, providing the Rx standard as (mostly) defined by ReactiveX. It has no other dependencies.
  • RxCocoa: Provides Cocoa-specific capabilities for general iOS/macOS/watchOS & tvOS app development, such as Binders, Traits, and much more. It depends on both RxSwift and RxRelay.
  • RxRelay: Provides PublishRelay and BehaviorRelay, two simple wrappers around Subjects. It depends on RxSwift.
  • RxTest and RxBlocking: Provides testing capabilities for Rx-based systems. It depends on RxSwift.
... find compatible
... see the broader vision
  • Does this exist for Android? RxJava
  • Where is all of this going, what is the future, what about reactive architectures, how do you design entire apps this way? Cycle.js - this is javascript, but RxJS is javascript version of Rx.


Here's an example In Action
Define search for GitHub repositories ...
let searchResults = searchBar.rx.text.orEmpty
    .throttle(.milliseconds(300), scheduler: MainScheduler.instance)
    .flatMapLatest { query -> Observable<[Repository]> in
        if query.isEmpty {
            return .just([])
        return searchGitHub(query)
... then bind the results to your tableview
    .bind(to: tableView.rx.items(cellIdentifier: "Cell")) {
        (index, repository: Repository, cell) in
        cell.textLabel?.text = repository.name
        cell.detailTextLabel?.text = repository.url
    .disposed(by: disposeBag)


  • Xcode 10.2
  • Swift 5.0

For Xcode 10.1 and below, use RxSwift 4.5.


Rx doesn't contain any external dependencies.

These are currently the supported options:


Open Rx.xcworkspace, choose RxExample and hit run. This method will build everything and run the sample app


# Podfile

target 'YOUR_TARGET_NAME' do
    pod 'RxSwift', '~> 5'
    pod 'RxCocoa', '~> 5'

# RxTest and RxBlocking make the most sense in the context of unit/integration tests
    pod 'RxBlocking', '~> 5'
    pod 'RxTest', '~> 5'

Replace YOUR_TARGET_NAME and then, in the Podfile directory, type:

$ pod install


Officially supported: Carthage 0.33 and up.

Add this to Cartfile

github "ReactiveX/RxSwift" ~> 5.0
$ carthage update

Carthage as a Static Library

Carthage defaults to building RxSwift as a Dynamic Library.

If you wish to build RxSwift as a Static Library using Carthage you may use the script below to manually modify the framework type before building with Carthage:

carthage update RxSwift --platform iOS --no-build
sed -i -e 's/MACH_O_TYPE = mh_dylib/MACH_O_TYPE = staticlib/g' Carthage/Checkouts/RxSwift/Rx.xcodeproj/project.pbxproj
carthage build RxAlamofire --platform iOS

Swift Package Manager

Create a Package.swift file.

// swift-tools-version:5.0

import PackageDescription

let package = Package(
  name: "RxTestProject",
  dependencies: [
    .package(url: "https://github.com/ReactiveX/RxSwift.git", from: "5.0.0")
  targets: [
    .target(name: "RxTestProject", dependencies: ["RxSwift", "RxCocoa"])
$ swift build

To build or test a module with RxTest dependency, set TEST=1.

$ TEST=1 swift test

Manually using git submodules

  • Add RxSwift as a submodule
$ git submodule add git@github.com:ReactiveX/RxSwift.git
  • Drag Rx.xcodeproj into Project Navigator
  • Go to Project > Targets > Build Phases > Link Binary With Libraries, click + and select RxSwift-[Platform] and RxCocoa-[Platform] targets



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5.0.1 - Apr 30, 2019

  • Reverts Carthage integration from using static to dynamic libraries. #1960

5.0.0 - Apr 29, 2019

RxSwift 5 is a mostly source-compatible release targeting the Swift 5 compiler.

Xcode 10.2 is the minimum supported version (or Swift 5 on Linux).

If you're using Xcode 10.1 and below, please use RxSwift 4.5.

  • Relays have been moved to a separate framework - RxRelay, and can be used without RxCocoa. #1924
  • TimeInterval has been deprecated in favor of DispatchTimeInterval. For example - throttle(1.2) would change to throttle(.milliseconds(1200)), while throttle(3) would change to throttle(.seconds(3)). #1472
  • Variable is now entirely deprecated. #1922
  • do now provides additional "after" closures. For example, do(onNext:) and do(afterNext:). #1898
  • bind(to:) now supports multiple observers (e.g. bind(to: observer1, observer2)). #1702
  • Changes the return type of ObservableType.toArray to Single. #1923
  • Adds compactMap. #1925
  • Deprecate Completable.merge in favor of Completable.zip. #1929 #1931
  • RxSwift can be built as a Static Library using Carthage 0.33 and up. #1940


  • SubjectType.SubjectObserverType has been renamed to SubjectType.Observer. #1950
  • The S associated type has been renamed to Subject where applicable. #1950
  • The S generic constraint on SharedSequence has been renamed to SharingStrategy. #1951
  • The E associated type on ObservableConvertibleType and ObserverType have been renamed to Element. #1945
  • The C and S associated types have been renamed to Collection and Sequence accordingly. #1949
  • Renamed ElementType associatedtype to Element. #1945
  • Renamed TraitType associatedtype to Trait. #1945
  • Make RxMutableBox supported on Linux in Swift 5. #1917
  • Fix incorrect assignment to Thread.threadDictionary on Linux. #1912
  • combineLatest of an empty array now completes immediately. #1879
  • Add resultsSelector missing closure labels for some overloads of combineLatest & zip.

4.5.0 - Apr 1, 2019

  • Compatibility with Xcode 10.2.
  • Adds missing UISearchBar.setDelegate().

4.4.2 - Mar 10, 2019


  • Adds UIView.rx.backgroundColor Binder. #1888


  • Fix multiple disposes on ScheduledDisposables. #1892
  • Fix DelegateProxy main thread validation. #1882
  • Bring back the first operator to ObservableType. #1886

4.4.1 - Feb 9, 2019

  • Adds takeUntil(_ behavior:predicate:).


  • Fixes problems with RxAtomic and thread sanitizer. #1853
  • Fixes problem with passing 0 count to Observable.range. #1870
  • Fixes Swift 5.0 warnings. #1859
  • Fixes problem with RxCocoa and DISABLE_SWIZZLING flag. #1805
  • Internal cleanups:
    • Unused code deletions.
    • Adds SwiftLint.
    • Removes legacy Swift 3.0 conditional compilation flags.