How does an app with lower base sdk work?

Question

In XCode I can specify Base SDK. I am wondering how does that work behind the scenes? If I am running an app, for example, on a device that has iOS 7 and my base SDK is iOS

Answer 1

Base SDK is the SDK that you want to use to build the app. Use "Deployment target" to specify the minimum OS you want your app to run on.

If you want to know the iOS version, check out this question.