title: Xcode 9 : Module compiled with Swift 3.1 cannot be imported in Swift 4.0
body: <p>After updating to Xcode 9, I tried to build one of my projects.</p>
  
  <p>I use the <strong>FacebookLogin</strong> pod.
  I have a compiler error in FacebookLogin/LoginButton.swift</p>
  
  <pre><code>@testable import FacebookCore
  ❌ Module compiled with Swift 3.1 cannot be imported in Swift 4.0
  </code></pre>
  
  <p>In my target's build settings, the Swift language version is set to <strong>Swift 3.2</strong>.</p>
  
  <p><a href="https://i.stack.imgur.com/6jYoK.png" rel="noreferrer"><img src="https://i.stack.imgur.com/6jYoK.png" alt="Screenshot added"></a></p>
  
  <p>I guess I need to wait for Facebook to update their pod ? Or any other suggestion ?</p>
  
  <p>Thanks !</p>