ionic-framework/js/ext/angular/src/service/ionicLoading.js

angular.module('ionic.service.loading', ['ionic.ui.loading'])

.factory('Loading', ['$rootScope', '$document', '$compile', function($rootScope, $document, $compile) {
  return {
    /**
     * Load an action sheet with the given template string.
     *
     * A new isolated scope will be created for the 
     * action sheet and the new element will be appended into the body.
     *
     * @param {object} opts the options for this ActionSheet (see docs)
     */
    show: function(opts) {
      var defaults = {
        content: '',
        animation: 'fade-in',
        showBackdrop: true,
        maxWidth: 200,
        showDelay: 2000
      };

      opts = angular.extend(defaults, opts);

      var scope = $rootScope.$new(true);
      angular.extend(scope, opts);

      // Make sure there is only one loading element on the page at one point in time
      var existing = angular.element($document[0].querySelector('.loading-backdrop'));
      if(existing.length) {
        var scope = existing.scope();
        if(scope.loading) {
          scope.loading.show();
          return scope.loading;
        }
      }

      // Compile the template
      var element = $compile('<loading>' + opts.content + '</loading>')(scope);

      $document[0].body.appendChild(element[0]);

      var loading = new ionic.views.Loading({
        el: element[0],
        maxWidth: opts.maxWidth,
        showDelay: opts.showDelay
      });

      loading.show();

      scope.loading = loading;

      return loading;
    }
  };
}]);