Will old source code run with SDK 4.2?

I'v开发者_如何学Pythone been working on creating my own iPhone app with source code my company gave me. This code was created with iPhone SDK 3.0. I've worked on it for over a year (I'm a designer so my coding is mostly copy and paste) and to test the app on my iPhone it says I must update my SDK to 4.2. I'm wondering will this break my app? I probably don't have the skills in xcode to upgrade my code if I am required to rewrite parts.

Thanks,

Chris

If none of the code has been deprecated, changed or even removed, chances are good it still runs fine. Most projects run, and if you have used external code (and hopefully noted where you got it from) there might be an update available for that piece of code.

Just set the deployment target to iOS 3.0 in your project settings

here some little explanation: link