title: Cosmos: Update to Swift 4 reveals new issue: The following binaries use incompatible versions of Swift
body: <p>After I updated my App to Swift 4 I get this error message:
  error: <strong>The following binaries use incompatible versions of Swift:</strong>
  /Users/Konrad/Library/Developer/Xcode/DerivedData/ExploreYourCity-btthjezgywzvnmduiurzwgwzrven/Build/Products/Debug-iphoneos/Cosmos/Cosmos.framework/Cosmos
  /Users/Konrad/Library/Developer/Xcode/DerivedData/ExploreYourCity-btthjezgywzvnmduiurzwgwzrven/Build/Products/Debug-iphonesimulator/ExploreYourCity.app/ExploreYourCity
  I can not find a solution to this misstake. Whats wrong?</p>
  
  <p>Library setup method: CocoaPods
  Version of the library. Example: 12.0.1.
  Xcode version. Example:9.0.1.
  OS version. Example: iOS 11.0.
  *Swift Version: Swift 4.0.</p>