Reactive layout framework built on top of ReactiveCocoa
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ReactiveCocoaLayout is a framework for describing Cocoa and Cocoa Touch layouts in a reactive way, based on ReactiveCocoa.

This framework is very much a work in progress at the moment, and should be considered alpha quality. Breaking changes may happen often during this time.

Why Not Use Auto Layout?

RCL intends to offer the following advantages over Auto Layout:

  • Explicit and linear layout. Reactive layout proceeds in a linear fashion, making it easier to understand and debug the steps it takes along the way.
  • Top-down layout. A view's layout doesn't interact with its superview's layout unless the former's size or frame is explicitly incorporated in the latter's layout chain, creating a unidirectional relationship that leads to better encapsulation (no global priorities!) and less complexity. Bidirectional relationships are still possible, but must be made explicit.
  • Conditional layouts at runtime. RCL is built on the full power of ReactiveCocoa, and signals can be composed to dynamically disable and re-enable entire layout chains (like when you want to hide and show views) without actually modifying them.
  • Implicit animations. To animate the setting of a view's frame, simply add an animation method into the signal chain. No need to explicitly animate constants anywhere.
  • Incremental use. RCL can be used internally in views without any implementation details leaking out. Callers using Auto Layout or struts and springs can incorporate reactive views without knowing or caring how they perform layout internally. No UI-wide slowdowns or behavior changes just from using RCL!
  • Extensibility. RCL is made up of many independent bits of functionality unified into a framework. It's easy to extend it with your own functionality if you want it to behave differently.
  • Not a black box. Unlike AppKit and UIKit, RCL is an open source project, so you can crack open any particular bit and see why it behaves the way it does.

Getting Started

To start building the framework, clone this repository and then run script/bootstrap. This will automatically pull down any dependencies. Then, simply open ReactiveCocoaLayout.xcworkspace (note: not the .xcodeproj) and build.

To use ReactiveCocoaLayout in your project, you will need to include the ReactiveCocoaLayout.xcodeproj (note: not the .xcworkspace) file in your project, and link ReactiveCocoa and Archimedes into your application target.


ReactiveCocoaLayout is released under the MIT license. See