shuffle array in ng-repeat angular

I'm creating a quiz and every time I start the quiz I want to shuffle the questions, so that they won't appear in the same order every time.

I have this in my html code:

<div ng-repeat="question in questions | filter:ids | orderBy:randomSort">
    <div id="question">{{question.question}}</div><img id="nextImg" ng-src="../app/img/next.png" ng-click="next()" />
    <img class="quizImg" ng-hide="{{question.image}}==null" ng-src="{{question.image}}" />

    <div class="answer" ng-repeat="answer in question.answers">
        <input type="radio" ng-click="checked(answer)">{{answer.answer}}
    </div>
    <!--input id="nextQuestion" type="button" ng-click="next()" value="{{buttonText}}"-->
</div>

and this in my controller

 lycheeControllers.controller('quizCtrl', ['$scope', '$http', function ($scope, $http) {
    $http.get('json/questions.json').success(function (data) {
        //all questions
        $scope.questions = data;

        $scope.titel = "Check your knowledge about lychees"


        $scope.randomSort = function(question) {
                      return Math.random();
                    };

        //filter for getting answers / question
        $scope.ids = function (question) {
            return question.id == number;
        }

        $scope.find = function (id) {
            if (id == number) {
                return true;
            }
        }


        $scope.next = function () {
            if (!(number == (data.length))) {
                //questionId++;
                number++;
                if (correct == true) {
                    points++;
                }
                //alert(points);
            } else {
                if (!end) {
                    if (correct == true) {
                        points++;
                        end = true;
                    }
                }

                alert("Quiz finished: your total score is: " + points);
            }
            correct = false;
        }

        $scope.checked = function (answer) {
            //alert(answer.answer);

            if (answer.correct == "yes") {
                correct = true;
            } else {
                correct = false;
            }

            //alert(correct);
        }


    });

}])
;

unfortunately this isn't working at all..