Hi what is open tool chain in iphone applications development, i want to learn it from scratch . is there any link that can help me to learn. Thanx
It means developing using tools independent from the iPhone SDK. It mainly has the set of opensource compilation tools (gcc, etc.) and API headers constructed by reverse engineering.
Non-Mac OS X environment, e.g. Windows and iPhoneOS need the open toolchain to target iPhone as the SDK is Mac-only. Legally, the SDK license prohibit development for iPhone projects not for AppStore, so the open toolchain must be used for apps on jailbroken platforms.
You can find detailed info in http://www.saurik.com/id/4.
(If you're targeting AppStore, you can forget this term.)
I would recommend iPhone Open Application Development, 2nd Edition By: Jonathan Zdziarski.
It's the best overall resource I've found on Open Tool and it's a decent if somewhat dated introduction to iPhone programming in general.
However, I would caution you that the market for open tool software is very small. I think the only people who really use it for anything significant beyond amusement are enterprise developers who want to highly customize their company's iPhone use. If your thinking about basing a mass market business on Open Tool I would do some research on how profitable that is likely to be before jumping in.