https://github.com/chrismiles/CMTraerPhysics
CMTraerPhysics is a port of the Traer v3.0 physics engine to Objective-C/Cocoa by Chris Miles.
The Traer physics engine was originally created by Jeffrey Traer Bernstein http://murderandcreate.com/physics/
Parts of this project were ported from traerAS3 by Arnaud Icard https://github.com/sqrtof5/traerAS3
Some of the demos are based on example code by Arnaud Icard.
CMTraerPhysics is open source, released under an MIT license.