title: How do you conditionally include a framework in an Xcode project?
body: <p>Is it possible to have a single Xcode project (and ideally a single target) that will conditionally include frameworks when built against a certain version of OS X / Xcode but not include those frameworks when built against another version? </p>
  
  <p>I'd like to begin adding support for El Capitan to an application I'm working on but some of the support I have in mind requires linking against frameworks that are not present in Yosemite. Is there a way to configure an Xcode project so that the same project can be built under 10.11 / Xcode 7 with the frameworks but also built under 10.10 / Xcode 6 without the frameworks (and without throwing an error)?</p>
  
  <p>I'm aware of how to check for the existence of a class or method at runtime, but it's not clear to me how I control the framework linking without creating a second Xcode project, a second source control branch or always building against Xcode 7 (none of which I want to do, yet). </p>