angularjs：$timeout使用(服务内部)

我正在尝试制作一个小通知器,通知典型情况：需要授权,保存更改等.通知显示3秒钟后消失,如果用户没有点击它(如果点击通知,它立即消失).
文档资料不多.
我该如何使用$timeout来调用close(); 3秒后？
我怎样才能将变量(nId)放入函数中？我在默认的setTimeOut()中尝试使用closure(* function(){return function(){}} *),但没有成功.

myApp.controller('noticesCtrl',function noticesCtrl($scope,$rootScope,noticesData){
        $rootScope.notices = [];
        $scope.closeNotice = function(nId){
            noticesData.close(nId);
        };
    });

myApp.factory('noticesData',function($rootScope,$timeout){
    return{
        add: function(type,text){
            var nId = $rootScope.notices.length + 1;
            $rootScope.notices.push({id: nId,type:type,text:text+nId});
            // call close function with 3sec. delay; how?
        },close: function(nId){
            angular.forEach($rootScope.notices,function(notice,key){
                if(notice.id == nId){
                    $rootScope.notices.splice(key,1);
                }
            });
        }
    }
});

myApp.factory('noticesData',$timeout){
    var obj = {};
    obj.add = function(type,text){
        var nId = $rootScope.notices.length + 1;
        $rootScope.notices.push({id: nId,text:text+nId});
        $timeout(function(){
            obj.close(nId);
        },3000);
    }
    obj.close = function(nId){
        angular.forEach($rootScope.notices,key){
            if(notice.id == nId){
                $rootScope.notices.splice(key,1);
            }
        });
    }
    return obj; 
});