Upgraded to SDK 4.1 and can no longer build for iOS 4.0

Just u开发者_运维知识库pgraded my xcode to the latest SDK which has the iOS 4.1 SDK. My app was built for 4.0, but xcode is no longer letting me build for 4.0 (The SDK is missing). I'd prefer not to require 4.1 yet as the app doesn't need it and it just came out yesterday. Any ideas to allow me to build for 4.0? I don't see an option to download the last version of xcode from the developer website.

It is a common misunderstanding that because it is called Base SDK it should refer to the minimum requirement of your app. It is not so! The Base SDK is the highest SDK you will develop against and it makes sense to keep it updated to the latest features and iOS version (all you do is just not use any of the new functionality if you don't want to). If you plan to support older versions of iOS instead, what you have to do is set the Deployment Target to the minimum SDK level you want to support.

It has taken me a while and a fair amount of reading to work this out. This is the basic idea. If you need more info, a more complete explanation of this is available in one of my posts.

This is the usual way things end when you upgrade the SDK. You set the base SDK to the latest version (4.1, in your case) and set the deployment target to whatever you want. The binary will run on older devices according to your deployment target setting. See also some of the older questions asked after previous SDK update.