title: unexpectedly found nil while unwrapping an Optional value from NSMutableString
body: <p>I can't get around this error. When I run this function I get a fatal error. fatal error: unexpectedly found nil while unwrapping an Optional value
  below is the function:</p>
  
  <pre><code>func changeSelectedFontColor(fontColor: UIColor) {
  
      let selectedRange : NSRange = self.textView.selectedRange
  
      var currentAttributesDict : NSDictionary = textView.textStorage.attributesAtIndex(selectedRange.location, effectiveRange: nil)
  
      var currentFont : UIFont = currentAttributesDict.objectForKey(NSFontAttributeName) as UIFont
  
      let italFont = [NSFontAttributeName:UIFont(name: "Georgia-Italic", size: 18.0)]
  
      var currentColor : UIColor = currentAttributesDict.objectForKey(NSForegroundColorAttributeName) as UIColor
  
      var currentBGColor : UIColor = currentAttributesDict.objectForKey(NSBackgroundColorAttributeName) as UIColor
  
      var currentUnderlinedText : UIFont = currentAttributesDict.objectForKey(NSUnderlineStyleAttributeName) as UIFont
  
      var currentparagraphStyle : NSMutableParagraphStyle = currentAttributesDict.objectForKey(NSParagraphStyleAttributeName) as NSMutableParagraphStyle
  }
  </code></pre>