$ionicLoading display dynamic value

1

How can i display a dynamic value inside of ionicLoading?
here is my code but it always shows 0 - initialized value:

                  $rootScope.updateProgress = 0;
                  $ionicLoading.show({
                    template: 'Updating...' + $rootScope.updateProgress
                  });

And later in my code i update this $rootScope.updateProgress value:

            var iPecent = Math.round(downloadProgress.receivedBytes / downloadProgress.totalBytes * 100);
            $rootScope.$apply(function () {
              $rootScope.updateProgress = iPecent;
            });