title: “Swift Language Version” error in an Objective C app
body: <p>Dealing with an Objective C iOS app (working fine); when I start to set some Core Data entities up, as soon as I compile I get this error message:</p>
  
  <pre><code>The “Swift Language Version” (SWIFT_VERSION) build setting must be set to a supported value for targets which use Swift. This setting can be set in the build settings editor.
  </code></pre>
  
  <p>I am using Xcode Version 9.4.1 and there is no <code>SWIFT_VERSION</code> in the build settings editor.
  And if I eliminate the Core Data entity I just set up, the problem goes away.</p>
  
  <p>I'd be happy if someone had an explanation and told me what to do.
  I am somewhat surprised to see this message related to “Swift Language Version”, when my app is only in Objective C. But I presume some dependency may be using Swift.</p>