title: App did Build but it doesn't run fatal error: unexpectedly found nil while unwrapping an Optional value
body: <p>I'm getting the error between "let completePath" and "let nameOfPathHistory".even if I print something in between, I got the "Fatal error"  The function that I'm calling with completePath returns the value that it should return. </p>
  
  <p>What is very strange for me is that when I build the App everything looks OK but when I run it then it appears the FATAL ERROR and the break point.</p>
  
  <p>Does someone have an Idea why I'm getting this error?</p>
  
  <pre><code>class ViewController: UIViewController {
  
  @IBOutlet var datePickerCpntainer: UIView!
  @IBOutlet var selectedValueLabel: UILabel!
  @IBOutlet var selectValuesButton: UIButton!
  
  @IBOutlet var selectDate: UIButton!
  
  @IBOutlet var historyImageView: UIImageView!
  var selectedValuefromPicker:String! = ""
  var selectedChildInPicker: String! = ""
  var childValueString: String! = ""
  
  var selectedDateInPickerBeginn: String! = ""
  var timeStampBeginn:String! = ""
  
  var selectedDateInPickerEnde:String! = ""
  var timeStampEnde:String! = ""
  
  @IBOutlet var greatView: UIView!
  @IBOutlet var containerView: UIView!
  
  //var containerViewState : Bool
  
  override func viewDidLoad() {
      super.viewDidLoad()
  
      selectValuesButton.layer.borderColor = UIColor.whiteColor().CGColor
      selectValuesButton.layer.borderWidth = 1
      selectValuesButton.layer.cornerRadius = 10
  
      selectDate.layer.cornerRadius = 10
      let catchPath = CatchPath()
  
          selectedValueLabel.text = selectedValuefromPicker
          childValueString = selectedChildInPicker
  
      print("-------------&gt;\(childValueString)")
              timeStampBeginn = selectedDateInPickerBeginn
              timeStampEnde = selectedDateInPickerEnde
  
      print("------------------\(timeStampEnde)")
  
              let completePath = catchPath.CatchThePathWithChid(childValueString,dateBeginn: timeStampBeginn, dateEnde: timeStampEnde)
  
              print(completePath)
  
  
  
              let nameOfPathHistory = catchPath.downloadPath(completePath, encoding: NSUTF8StringEncoding)
  
  
              ImageLoader.sharedLoader.imageForUrl(nameOfPathHistory, encoding: NSUTF8StringEncoding) { (image, url)  in
  
                  self.historyImageView.image = image!
              }
  
  }
  
  
  
  
  @IBAction func selectItem(sender: AnyObject) {
  
      containerView.hidden = false
  
      func UIColorFromRGB(rgbValue: UInt) -&gt; UIColor {
          return UIColor(
              red: CGFloat((rgbValue &amp; 0xFF0000) &gt;&gt; 16) / 255.0,
              green: CGFloat((rgbValue &amp; 0x00FF00) &gt;&gt; 8) / 255.0,
              blue: CGFloat(rgbValue &amp; 0x0000FF) / 255.0,
              alpha: CGFloat(0.5)
          )
      }
  
  
  
      greatView.backgroundColor = UIColorFromRGB(0x5e9400)
      historyImageView.alpha = 0.5
      selectValuesButton.alpha = 0.5
      selectDate.alpha = 0.5
  
  
  }
  
  
  @IBAction func selectDate(sender: AnyObject) {
  
      datePickerCpntainer.hidden = false
  }
  
  
  }
  </code></pre>
  
  <p><strong>update catchPath structure</strong></p>
  
  <pre><code>import Foundation
  import UIKit
  
  public struct CatchPath {
  
  
  
  func downloadPath ( contentsOfURL: NSURL, encoding: NSStringEncoding) -&gt; String{
     var namePath:String = "http://wetter.htw-berlin.de/"
  
      do {
          let content = try String(contentsOfURL: contentsOfURL, encoding: encoding)
  
  
          namePath += content
          print(namePath)
      }
  
      catch {
          print(error)
      }
  
      return namePath
  
  }
  func CatchThePathWithChid (chidValue:String?,dateBeginn:String?, dateEnde:String?)-&gt; NSURL {
  
      var completePathImage = NSURL(string: "")
  
  
      let completePathWitValuePicker = NSURL(string: "http://wetter.htw-berlin.de/phpFunctions/holePlot.php?begin=\(dateBeginn) &amp;end=\(dateEnde)&amp;\(chidValue)")
  
      if chidValue != nil &amp;&amp; dateBeginn != ""  {
  
        var  completePath = NSURL(string: "http://wetter.htw-berlin.de/phpFunctions/holePlot.php?begin=\(dateBeginn) &amp;end=\(dateEnde)&amp;\(chidValue)")
  
         completePathImage = completePath
  
      } else  {
  
          let wetterURLString = NSURL(string: "http://wetter.htw-berlin.de/phpFunctions/holePlot.php?begin=1365976800&amp;end=1366063200&amp;chid[]=6")
  
          completePathImage = wetterURLString
  
  
      }
  
  
  
      print ("--------------------------&gt;\(completePathImage)")
  
  
  
  
      return completePathWitValuePicker!
  }
  
  }
  </code></pre>