iOS compatibility

I'm releasing an iPhone app and want it to have the largest possible audience. What version of iOS s开发者_开发问答hould I compile it with?

The app doesn't use any new iOS 4 capabilities

You could set your "Base SDK" to the latest (iOS 4.2) and your "iOS Deployment Target" to iOS 3.0. Do make sure to check that you aren't using code that's not available on iOS 3.0.

Personally, I think it'd be okay to just set it to 3.1.3...

EDIT I haven't tried it yet but it looks like this would be a useful question to favorite.. finding unsupported apis with os version

Welcome to the jungle if you are really determined to make your app available for iOS as ancient as 3.0...

A few things that might be able to save your life:

1. Wrap up your code properly, check this post .
2. Go to iOS Dev Center and search the keyword API Diffs, read those documents and make sure you don't apply any iOS 4 APIs in your code.
3. Be sure to test your app in real iOS 3.x devices, jailbreak ones preferred (since jailbreak is one of the major reasons for people still sticking to iOS 3.x).

And finally, remember to set the project's deployment target to 3.x. Good luck. :-)