title: Error using LinkingObjects(fromType:property:) - Use of unresolved identifier 'LinkingObjects'
body: <p>Following the Realm Swift documentation i declared some classes <code>Car</code> and <code>Tour</code> like this: </p>
  
  <pre><code>import RealmSwift
  
  
  class Car: Object {
     dynamic var id = ""
     let tours = List&lt;Tour&gt;()
  }
  
  class Tour: Object {
     dynamic var id = "" 
     let cars = LinkingObjects(fromType: Car.self, property: "tours")
  }
  </code></pre>
  
  <p>When I try to build this, i get an error: <code>Use of unresolved identifier 'LinkingObjects'</code>. I tried to clean Xcode's Derived Data like <a href="https://stackoverflow.com/questions/37409089/getting-error-use-of-unresolved-identifier-linkingobjects">this</a> post says, but the build still fails. </p>
  
  <p>Does anyone know, how to resolve this error?</p>