Phgraph-for-iphone is a project mainly written in Objective-C, it's free.
Port of OSX PHGraph for use on the iPhone
This a port of PHGraph http://www.mpkju.fr/~graphview/ by Pierre-Henri Jondot for use on the iPhone.
Add the files to your iPhone application Add an import #import "PHGraphView.h" Create a view based on the PHGraphView Add data, axis, etc...
See these examples for usage: http://www.mpkju.fr/~graphview/page1/page1.html