RxSwift: ReactiveX for Swift

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

• why use rx?
• the basics, getting started with RxSwift
• traits - what are Single, Completable, Maybe, Driver, and ControlProperty ... and why do they exist?
• testing
• tips and common errors
• debugging
• the math behind Rx
• what are hot and cold observable sequences?

... install

• Integrate RxSwift/RxCocoa with my app. Installation Guide

... hack around

• with the example app. Running Example App
• with operators in playgrounds. Playgrounds

... interact

• All of this is great, but it would be nice to talk with other people using RxSwift and exchange experiences.
  Join Slack Channel
• Report a problem using the library. Open an Issue With Bug Template
• Request a new feature. Open an Issue With Feature Request Template
• Help out Check out contribution guide

... compare

• with other libraries.

... understand the structure

RxSwift comprises five separate components depending on each other 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 Shared Sequences, Traits, and much more. It depends on both RxSwift and RxRelay.
• RxRelay: Provides PublishRelay, BehaviorRelay and ReplayRelay, three simple wrappers around Subjects. It depends on RxSwift.
• RxTest and RxBlocking: Provides testing capabilities for Rx-based systems. It depends on RxSwift.

... find compatible

• libraries from RxSwiftCommunity.
• Pods using RxSwift.

... 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.

Usage

Here's an example	In Action
Define search for GitHub repositories ...
let searchResults = searchBar.rx.text.orEmpty .throttle(.milliseconds(300), scheduler: MainScheduler.instance) .distinctUntilChanged() .flatMapLatest { query -> Observable<[Repository]> in if query.isEmpty { return .just([]) } return searchGitHub(query) .catchAndReturn([]) } .observe(on: MainScheduler.instance)
... then bind the results to your tableview
searchResults .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)

Requirements

• Xcode 12.x
• Swift 5.x

For Xcode 11 and below, use RxSwift 5.x.

Installation

RxSwift doesn't contain any external dependencies.

These are currently the supported installation options:

Manual

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

CocoaPods

# Podfile
use_frameworks!

target 'YOUR_TARGET_NAME' do
    pod 'RxSwift', '6.0.0-rc.2'
    pod 'RxCocoa', '6.0.0-rc.2'
end

# RxTest and RxBlocking make the most sense in the context of unit/integration tests
target 'YOUR_TESTING_TARGET' do
    pod 'RxBlocking', '6.0.0-rc.2'
    pod 'RxTest', '6.0.0-rc.2'
end

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

$ pod install

XCFrameworks

Each release starting with RxSwift 6 includes *.xcframework framework binaries. Simply drag the needed framework binaries to your Frameworks, Libraries, and Embedded Content section under your target's General tab.

Carthage

Add this to Cartfile

github "ReactiveX/RxSwift" "6.0.0-rc.2"

$ 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 RxSwift --platform iOS

Swift Package Manager

Note: There is a critical cross-dependency bug affecting many projects including RxSwift in Swift Package Manager. We've filed a bug (SR-12303) in early 2020 but have eno answer yet. Your mileage may vary.

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", .exact("6.0.0-rc.2"))
  ],
  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 [email protected]:ReactiveX/RxSwift.git

• Drag Rx.xcodeproj into Project Navigator
• Go to Project > Targets > Build Phases > Link Binary With Libraries, click + and select RxSwift, RxCocoa and RxRelay targets

References

• http://reactivex.io/
• Reactive Extensions GitHub (GitHub)
• RxSwift RayWenderlich.com Book
• Boxue.io RxSwift Online Course (Chinese 🇨🇳)
• Erik Meijer (Wikipedia)
• Expert to Expert: Brian Beckman and Erik Meijer - Inside the .NET Reactive Framework (Rx) (video)
• Reactive Programming Overview (Jafar Husain from Netflix)
• Subject/Observer is Dual to Iterator (paper)
• Rx standard sequence operators visualized (visualization tool)
• Haskell