How to find iOS 4 only code in iPhone project

i have a iPhone Project with Base SDK 4.0 and Deployment Target set to 3.0 with XCode 3.2.3. Is there an "easy" way to find out whether i use iOS 4 only API calls in my Source Code. I'm aware that i could install an old XCode to run my project against an e.g. 3.1.3 Simulator, but i hope there is a simpler way for checking this.

Anybody has an idea?

Thanks Ro开发者_Go百科land

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Set the SDK to a 3.x SDK and recompile. If you have any new errors or warnings, it's probably a sign you have 4.0-specific code, and the errors will tell you where.