My presentation of CMTraerPhysics, an Objective-C/Cocoa port of the Traer v3.0 physics engine for iOS.
Presented at Melbourne Cocoaheads March 2012.
Presentation video: http://vimeo.com/42195248
https://github.com/chrismiles/CMTraerPhysics
http://blog.chrismiles.info/2012/04/cmtraerphysics-spring-physics-engine.html