title: xcodebuild: Returned an unsuccessful exit code
body: <p>The fight with the following error after <code>pod spec lint BSTableViewReorder.podspec --verbose</code>:</p>
  
  <pre>
  === CLEAN TARGET BSTableViewReorder OF PROJECT Pods WITH CONFIGURATION Release ===
  
  Check dependencies
  “Use Legacy Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
  “Use Legacy Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
  
  ** CLEAN FAILED **
  
  
  The following build commands failed:
      Check dependencies
  (1 failure)
  === BUILD TARGET BSTableViewReorder OF PROJECT Pods WITH CONFIGURATION Release ===
  
  Check dependencies
  “Use Legacy Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
  “Use Legacy Swift Language Version” (SWIFT_VERSION) is required to be configured correctly for targets which use Swift. Use the [Edit > Convert > To Current Swift Syntax…] menu to choose a Swift version or use the Build Settings editor to configure the build setting directly.
  
  ** BUILD FAILED **
  
  
  The following build commands failed:
      Check dependencies
  (1 failure)
   -> BSTableViewReorder (1.4.3)
      - ERROR | [iOS] xcodebuild: Returned an unsuccessful exit code.
  
  Analyzed 1 podspec.
  
  [!] The spec did not pass validation, due to 1 error.
  </pre>
  
  <p>Any ideas how to workaround this?</p>