ios 5 xcode 4.2 doesn't have ios 4.3 as a base sdk option

Question

in xcode 4.2 I don't have any option to choose a different base sdk other than ios 5. I want to make sure my app works for ios 4.2 and higher. How can I get these to show up?

Answer 1

In Xcode choose the deployment target OS:

From Apple's documentation:

iOS Deployment Target
Code will load on this and later versions of iOS. Framework APIs that are unavailable in earlier versions will be weak-linked; your code should check for null function pointers or specific system versions before calling newer APIs.

Base SDK
The name or path of the base SDK being used during the build. The product will be built against the headers and libraries located inside the indicated SDK. This path will be prepended to all search paths, and will be passed through the environment to the compiler and linker.

Answer 2

In Target sdk select a lower version of iOS.