title: App crashes in Release build but not in debug
body: <p>As I said in the title, I am writing an app for iPhone which runs perfectly in debug mode but when I build it as release and install it via TestFlight, it crashes. 
  Due to the crash log it might have to do something with this lines:</p>
  
  <pre><code>let path = NSBundle.mainBundle().pathForResource("PrinterList", ofType: "plist")
  if path != nil {
      let printerDic = NSDictionary(contentsOfFile: path!)
      let printerList = NSArray(array: printerDic.allKeys)
      printerNames = printerList as [String]
  }
  </code></pre>
  
  <p>I am using an framework from Brother to print without AirPrint, but I think thats not the problem because the app crashes before doing something with the framework.
  It crashes only in this ViewController where I execute these lines. I need the framework only in this ViewController as well.</p>