title: Swift Form Validation - Check if Int or String has been entered
body: <p>I am trying to validate a form to make sure the user has entered an integer number and not a string. I can check if the number is an integer as follows:</p>
  
  <pre><code> var possibleNumber = timeRetrieved.text
      convertedNumber = possibleNumber.toInt()
      // convertedNumber is inferred to be of type "Int?", or "optional Int"
  
      if convertedNumber != nil {
  
          println("It's a number!")
  
          totalTime = convertedNumber!
  
  
      }
  </code></pre>
  
  <p>My problem is I want to make sure the user has not entered any text, doubles etc. I only want integer numbers. The following code does not work because it evaluates true if the variable is an integer. What code should I use to evaluate if variable is not an integer?</p>
  
  <pre><code>if convertedNumber != nil  {
  
  
          let alertController = UIAlertController(title: "Validation Error", message: "You must enter an integer number!", preferredStyle: .Alert)
          let alertAction = UIAlertAction(title: "OK", style: UIAlertActionStyle.Destructive, handler: {(alert : UIAlertAction!) in
              alertController.dismissViewControllerAnimated(true, completion: nil)
          })
          alertController.addAction(alertAction)
          presentViewController(alertController, animated: true, completion: nil)
  </code></pre>