title: Failed to build an iOS app in Xcode 6
body: <p>My app is written in swift, and it works pretty well in the simulator. However, when I try to build it for my iPad, it says</p>
  
  <pre><code>"Cannot load underlying module for 'Foundation"
  "Cannot load underlying module for 'Foundation"
  "Cannot load underlying module for 'Foundation"
  "Cannot load underlying module for 'Foundation"
  </code></pre>
  
  <p>The iPad is in iOS 8, and the project is targeted for iOS 8</p>