title: String does not have a member named setValue for Core Data in Swift
body: <p>I have done NSFetchRequest on an entity in coreData like so</p>
  
  <pre><code>var request = NSFetchRequest(entityName: "Users")
  request.returnsObjectsAsFaults = false
  var results = context.executeFetchRequest(request, error: &amp;error)
  </code></pre>
  
  <p>I have the iterated through so I can get to the valueForKey object like so: </p>
  
  <pre><code>if results!.count &gt; 0 {
  
              for result: AnyObject in results! {
                  if let rStatus = result.valueForKey("relationshipStatus") as? String{
                      rStatus.setValue(self.RelationshipStatus.text, forKey: "relationshipStatus") //GETTING AN ERROR HERE SAYING STRING DOES NOT HAVE A MEMBER NAMED 'SET VALUE'
                      println("Current User updated status to core data")
                      context.save(&amp;self.error)
                  }
              }
          }
  </code></pre>
  
  <p>Although I am getting an error saying 'String does not have a member named setValue'. Is there anyway of getting around this as I want to set the particular key only?</p>
  
  <p>Thanks in advance</p>