title: Predicate to filter array of strings in SWIFT throws error saying NSCFString is not key-value coding
body: <p>Below is my code snippet</p>
  
  <pre><code>//Search Bar Delegate
  func searchBar(searchBar: UISearchBar, textDidChange searchText: String)
  {
      println(searchText)
      var predicate:NSPredicate=NSPredicate(format: "SELF CONTAINS[c] \(searchText)")!
      self.listItemToBeDisplayed=listItem.filteredArrayUsingPredicate(predicate)
      (self.view.viewWithTag(1) as UITableView).reloadData()
  
  }
  </code></pre>
  
  <p>Error I got:</p>
  
  <blockquote>
    <p>*** Terminating app due to uncaught exception 'NSUnknownKeyException', reason: '[&lt;__NSCFString 0x17405ef90> valueForUndefinedKey:]: this
    class is not key value coding-compliant for the key V.'</p>
  </blockquote>
  
  <p>I want to filter strings in array to be filtered by my search string. If my search string is contained in any of the string in array, then it should be listed.</p>