This is a basic framework for an expression tree system written in Objective-C including the parsing of expressions from strings. It's been written primarily with the iPhone in mind but should compile just as easily for the Mac. To get started take a look at the included example project.
JamesRandall/Objective-C-Expression-Tree-Framework
An Objective-C framework suitable for use on the iPhone that implements expression trees, including parsing from strings.
Objective-CMIT