##Using UIAlertController with NSLocalizedString
Because I tend to localize everything in my apps, UIAlertController needed to be localized as well. So, I wrote a struct to simplify the way I use NSLocalizedWithString (which happens to be a long piece of code), and so I could use it in all my classes.

Use an extension (remember, an extension is like a category in Obj-c)

    extension String {

       var localized: String {
          return String.localizedStringWithFormat(NSLocalizedString(self,comment: ""))
       }

       func localizedWithComment(comment:String) -> String {
          return String.localizedStringWithFormat(NSLocalizedString(self,comment: comment))
       }
    }


Use Constants for better manipulation

    let errortitle = "alertErrorTitle".localized
    let errormessage = "alertErrorMessage".localized
    let cancel = "cancelAlert".localized

And the AlertController piece of code:

    func showAlertError(){

        var alertController = UIAlertController(title: errortitle,
                                            message: errormessage,
                                            preferredStyle: .Alert)

        let cancelAction = UIAlertAction(title: cancel, style: .Cancel) {
          (action) in
          //whatever action you want,  put it here
        }
        alertController.addAction(cancelAction)
        presentViewController(alertController, animated: true, completion: nil)
    }