$ionicLoadingConfig

var app = angular.module('myApp', ['ionic'])
app.constant('$ionicLoadingConfig', {
  template: 'Default Loading Template...'
});
app.controller('AppCtrl', function($scope, $ionicLoading) {
  $scope.showLoading = function() {
    $ionicLoading.show(); //options default to values in $ionicLoadingConfig
  };
});