How to add a "Base SDK" in XCode 4?

I currently use XCode 4.0 with Base SDK 4.3.

I would like to co开发者_运维问答mpile my app with an older SDK, for example 4.2, but I don't have this possibility as I have no other choice than SDK 4.3.

Do you know how to add older SDKs than the default Base SDK 4.3 proposed ?

Thanks a lot !

You cannot do that. Xcode versions are released along with iOS SDK's. They are linked together i.e particular Xcode version can compile the code on the specific iOS SDK only (which it come with by default). To compile your code in lower version of SDK, you need to download the lower version of Xcode

by changing the iosdeployment target you can run this.

for this, go to the targets in the xcode and get the info .There you can find the second tab build.in that you have search field.type the ios deployment target.change that to 4.2.So that it can run on 4.2 also

In build settings, under Architechtures, you have something called as Base SDK .. you can change you base SDK there and set it to the latest ios version you have installed.