Unable to Build 3.1.3 Device on iPhone SDK 4? [duplicate]

This question already has an answer here: How to make an iPhone app compatible w开发者_如何学Pythonith multiple SDK (firmware) versions (1 answer) Closed 3 years ago.

I just installed iPhone SDK 4, and i couldnt build app on 3.1.3 devices?

it says the SDK 3.1.3 is missing, did apple remove the previous SDK?

How do we test on the previous iPhone OS version?

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Yes. 3.1.3 was removed. Make sure you read release notes before installing beta software ;)

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3.1.3 is deprecated for building, not as a target. More info in my community wiki on this, here:

Install xCode 3.2.3 w/ iPhone SDK 4, get "Base SDK missing", can't see other SDKs