使用对象数组中的id设置ui select值

好吧,我有这个格式的对象数组

$scope.itemArray = [
        {id: 1, name: 'first'},
        {id: 2, name: 'second'},
        {id: 3, name: 'third'},
        {id: 4, name: 'fourth'},
        {id: 5, name: 'fifth'},
    ];

$scope.selectedItem = $scope.itemArray[0];//this works fine
$scope.selectedItem = $scope.itemArray[0].id;//this doesn't works

这是html部分:

<ui-select ng-model="selectedItem">
    <ui-select-match>
        <span ng-bind="$select.selected.name"></span>
    </ui-select-match>
    <ui-select-choices repeat="item in itemArray | filter: $select.search">
        <span ng-bind="item.name"></span>
    </ui-select-choices>
  </ui-select>

我要做的是使用 id 但是我不能这么做。我确信我在某个地方是错的,而且对这个插件来说也是非常新的。请帮帮我。