title: Swift Optionals - Unexpectedly found nil when unwrapping an optional value
body: <p>I'm new to Swift and have been trying to wrap (ha) my head around optional values. As far as I can see - although I'm probably wrong - variables can be optional and therefore contain a nil value and these have to be accounted for in code.</p>
  
  <p>Whenever I hit the 'save' button in my application I get the error: 'fatal error: unexpectedly found nil while unwrapping an Optional value'. </p>
  
  <pre><code>@IBAction func saveTapped(sender: AnyObject) {
  
      //code to save fillup to Parse backend
  
      // if variable is not nil
      if let username = PFUser.currentUser()?.username {
  
          // set username equal to current user
          self.object.username = username
  
      }else{
  
          println("PFUser.currentUser()?.username contained a nil value.")
  
      }
  
      // if variable is not nil
      if let amount = self.amountTextField.text {
  
          //set amount equal to value in amountTextField
          self.object.amount = self.amountTextField.text
  
      }else{
  
          println("self.amountTextField.text contained a nil value.")
  
      }
  
      // if variable is not nil
      if let cost = self.costTextField.text {
  
          // set cost equal to the value in costTextField
          self.object.cost = self.costTextField.text
  
      }else{
  
          println("self.costTextField.text contained a nil value.")
  
      }
  
      // set date equal to the current date
      self.object.date = self.date
  
      //save the object
      self.object.saveEventually { (success, error) -&gt; Void in
  
          if error == nil {
  
              println("Object saved!")
  
          }else{
  
              println(error?.userInfo)
  
          }
  
  
      }
  
      // unwind back to root view controller
      self.navigationController?.popToRootViewControllerAnimated(true)
  
  }
  </code></pre>
  
  <p>Not sure if the error is because of something in this block of code or somewhere else - can provide the main class code if needed.</p>
  
  <p>Any help anyone can provided would be really appreciated as this has been bugging me for a while now. </p>