The version of xcode that supports Iphone OS 3.1.2(7D11)?

HELLO, I am working on XCODE 3.1.4 , my iphone have 3.1.2 os...But as this versi开发者_如何学编程on of xcode supports iphone os3.1.1 and below.. so plz help me as either tell me the newer version of xcode that supports iphone os 3.1.2 or should i downgrade my iphone os to 3.1.1,,

any assistance is really appreciated..

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Ideally, you should be using the latest version of Xcode, which is included with the iPhone SDK. You can download the SDK from the iPhone Developer Center.