ReactiveCocoaLayout is a framework for describing Cocoa and Cocoa Touch layouts
in a reactive way, based on
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
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
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
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
To start building the framework, clone this repository and then run
This will automatically pull down any dependencies. Then, simply open
ReactiveCocoaLayout.xcodeproj and build.
To use ReactiveCocoaLayout in your project, you will need to link
Archimedes into your application target.
ReactiveCocoaLayout is released under the MIT license. See