Angularjs: How to display loading-icon when using ‘resolve’ in $routeProvider?

Not exactly sure whether this would work in your code as you have $resource integration.
But it may be worth to look into angular events: $routeChangeStart and $routeChangeSuccess.

in html:

<span ng-show="isViewLoading"> loading the view... </span>

in controller (which defines the scope of the html above):

$scope.isViewLoading = false;
$scope.$on('$routeChangeStart', function() {
  $scope.isViewLoading = true;
});
$scope.$on('$routeChangeSuccess', function() {
  $scope.isViewLoading = false;
});
$scope.$on('$routeChangeError', function() {
  $scope.isViewLoading = false;
});