##使用说明
var cityViewController:CityViewController = CityViewController(nibName: "CityViewController", bundle: nil);
self.presentViewController(cityViewController, animated: true) { () -> Void in
}
##使用说明
var cityViewController:CityViewController = CityViewController(nibName: "CityViewController", bundle: nil);
self.presentViewController(cityViewController, animated: true) { () -> Void in
}