问题
I’ve installed Snow Leopard, have Xcode 3.2 and 3.0 iPhone SDK. I want my applications to run on 2.2.1, but the SDK is nowhere to be found in Xcode. I’ve set the deploy target to 2.2.1, but still I cannot be sure I am not using any 3.0-isms. (I’ve sent a sample application to my friend who still has 2.2.1 and it does not run, so it looks I really do use some 3.0 specific API.) How can make sure that my applications will run on 2.2.1? (Simulator also lists only 3.0 as version option.) I’d hate to check my sources manually for every call that might not have existed in 2.2.1.
回答1:
See my question.
However, I think this is a bad situation that Apple has created for us. There really is no way to test against 2.x.x, if you, like me, have no iPhone 2.2s to test against. I actually bought a new 3Gs just so I could use the old 3G for testing. Stupidly though, when iTunes came up one day and asked if I wanted my phone updated to 3.0.1, I said yes, without realizing which phone I was updating.
I have tried, to no avail, to downgrade to 2.2.1, doing all the things like holding the home button and power for 10 seconds, etc., but I keep getting a baseband loading error.
I know Apple is trying hard to push everyone to 3.0, but not having the stats on how many users are still on the older OS, it seems prudent to keep supporting that OS. They should at least have kept 2.2.x support for the Simulator. I hate to release a 2.2.1 app based on whether I think I am using 3.0 calls or not, without actually testing it on 2.2.1.
回答2:
OK, SDK 3.1 was released yesterday (September 9) and also contains SDK 2.2.1. You cannot build for the Simulator, only for the device, but most of the glaring 3.0-isms will appear as compile errors, which makes testing much easier.
回答3:
Uninstall the SDK or Developer folder completley.
using Terminal execute: /Library/uninstall-devtools --mode=all, then restart, re-install new SDK.
来源：https://stackoverflow.com/questions/1397756/developing-for-2-2-1-sdk-on-snow-leopard