Init checkbox angularjs on ng-repeat

I've got this situation:

<md-subheader class="md-no-sticky">
            <span data-ng-if="itemSelected == undefined || itemSelected == ''">Choose</span>
            <span data-ng-if="itemSelected != '' || itemSelected != undefined"></span>
        </md-subheader>
        <md-list-item ng-repeat="item in items">
            <p>  </p>
            <md-checkbox class="md-secondary" ng-init="itemSelection" ng-model="itemSelection" ng-change="changeItemSelected(item)"></md-checkbox>
        </md-list-item>

In which i've got a list of items that you can select using a checkbox. The function on ng-change is this:

$scope.changeItemSelected = function(item) {
        $scope.itemSelected = item.name;
    };

When the controller starts, I call a service that get the data checked before. So if the data is not undefined (it means that before something was checked) I set this itemSelection as true. As you can see this variable is used on ng-init. It's working, but not too much. In this way it selects all the checkboxes and not the one i want. I can't reproduce the init call. I created a jsfiddle with this situation by the way http://ift.tt/2jJ9UoU try to think that when the jsfiddle starts it fires a call to the server to get one of the item selected before. For example i want select the third item of the list. because the server returns the third data like this:

{"data":{orange},"meta":{"code":200}}

something like that