title: fatal error: can not increment endIndex
body: <p>For some reason I get </p>
  
  <blockquote>
    <p>fatal error: can not increment endIndex</p>
  </blockquote>
  
  <p>at line myRange. Why I am getting this error? I don't understand whats wrong with my code.</p>
  
  <pre><code>import UIKit
  
  class ViewController: UIViewController {
  
  @IBOutlet var drag: UIPanGestureRecognizer!
  @IBOutlet weak var currentLabel: UILabel!
  @IBOutlet weak var label1: UILabel!
  @IBOutlet weak var label2: UILabel!
  @IBOutlet weak var label3: UILabel!
  @IBOutlet weak var label4: UILabel!
  @IBOutlet weak var label5: UILabel!
  @IBOutlet weak var label6: UILabel!
  @IBOutlet weak var label7: UILabel!
  @IBOutlet weak var label8: UILabel!
  @IBOutlet weak var label9: UILabel!
  
  let letter = "OX"
  var currentLetter = Character!()
  var decide = 0
  var labelArray = [UILabel]()
  var moveCounter = 0
  override func viewDidLoad() {
      super.viewDidLoad()
      getCurrentLetter()
      labelArray = [label1,label2,label3,label4,label5,label6,label7,label8,label9]
  }
  
  func getCurrentLetter()
  {
      let myRange = Range&lt;String.Index&gt;(start: letter.startIndex.advancedBy(decide), end: letter.startIndex.advancedBy(decide+1))
      currentLabel.text = letter.substringWithRange(myRange)
      currentLetter = Character(letter.substringWithRange(myRange))
  }
  
  func reset() {
      decide = 0
  }
  @IBAction func dragObject(sender: UIPanGestureRecognizer) {
      let points = sender.locationInView(view)
      let currentPoints = currentLabel.frame.origin
      currentLabel.center = CGPointMake(points.x, points.y)
      for item in labelArray {
          if CGRectContainsPoint(item.frame, points) {
              item.text = String(currentLetter)
              decide++
              drag.enabled = false
              currentLabel.center = currentPoints
          } else if drag.enabled == false {
              decide++
              drag.enabled = true
              currentLabel.center = currentPoints
          }
          if decide == 2 {
            reset()
          }
          getCurrentLetter()
        }
     }
  }
  </code></pre>