title: Swift | assigning nil to string
body: <p>I am writing an app using <strong>Parse.com</strong>.</p>
  
  <pre><code>func getContactsWithComplition(closure:() -&gt; ())
  {
      contactArray=[];
      if (PFUser.currentUser() != nil)
      {
          var realtion: PFRelation=PFUser.currentUser()["contactsOfUser"] as PFRelation;
          var query: PFQuery=realtion.query() as PFQuery;
          query.findObjectsInBackgroundWithBlock({ (contactsArray:[AnyObject]! , error:NSError!) -&gt; Void in
           if(error == nil)
           {
  
              for aContact in contactsArray
              {
              var cont=contact(phone: aContact["phoneNumber"] as String, firstName: aContact["name"] as String, lastName: aContact["familyName"] as String, adress: aContact["adress"] as String, email: aContact["email"] as String, role: aContact["role"] as String, note: aContact["note"] as String)
                  contactArray.append(cont)
  
              }
              closure()
  
           }
          else
           {
              println(error);
              }
          })
  
  
      }
      else
      {
          println("suck")
      }
  }
  </code></pre>
  
  <p>When the value of one of the sections is undefined, it returns <strong>nil</strong>, that can't be referenced as <strong>String</strong>.
  <br>
  How can I solve it?</p>