reactivecocoa/reactivecocoa

ReactiveCocoa is a Swift framework for Apple platforms (iOS, macOS, watchOS, tvOS) that brings a programming style called reactive programming to Cocoa, Apple's layer of frameworks for building apps. The core idea is to treat values as streams that change over time, and to describe your app's behavior as reactions to those changes rather than writing imperative step-by-step code. In practice, ReactiveCocoa wraps Apple's built-in UI components so that changes in one place automatically flow to another. For example, you can bind a text label to a data model's name property so the label updates whenever the name changes, without writing an explicit update call. User interactions like toggle switches, text fields, and button presses are exposed as streams of values you can map, filter, and chain together. It also supports intercepting Objective-C method calls and observing object lifetimes, which is useful for cleanup and lifecycle management. The framework sits on top of ReactiveSwift, which provides the underlying primitives (Signals, SignalProducers, and Actions). ReactiveCocoa then adds the Apple-specific UI bindings on top of those primitives. A developer would use this when building iOS or macOS apps and wanting to keep UI state and data in sync without writing repetitive boilerplate update code, particularly in apps where many parts of the interface react to shared data or user input. It is written in Swift 5 and can be added via CocoaPods, Carthage, or Swift Package Manager.