Javascript 如何从 AngularJS 中的变量设置 iframe src 属性

我试图从变量中设置IFRAME的src属性，但我无法使其工作……

标记:

<div class="col-xs-12" ng-controller="AppCtrl">

    <ul class="">
        <li ng-repeat="project in projects">
            <a ng-click="setProject(project.id)" href="">{{project.url}}</a>
        </li>
    </ul>

    <iframe  ng-src="{{trustSrc(currentProject.url)}}">
        Something wrong...
    </iframe>
</div>

控制器/app.js:

function AppCtrl ($scope) {

    $scope.projects = {

        1 : {
            "id" : 1,
            "name" : "Mela Sarkar",
            "url" : "http://blabla.com",
            "description" : "A professional portfolio site for McGill University professor Mela Sarkar."
        },

        2 : {
            "id" : 2,
            "name" : "Good Watching",
            "url" : "http://goodwatching.com",
            "description" : "Weekend experiment to help my mom decide what to watch."    
        }
    };

    $scope.setProject = function (id) {
        $scope.currentProject = $scope.projects[id];
        console.log( $scope.currentProject );

    }
}

使用这段代码时，不会在iframe的src属性中插入任何内容.只是一片空白.

Update 1:

Update 2:

Update 3:

$scope.setProject = function (id) {
    $scope.currentProject = $scope.projects[id];
    $scope.currentProjectUrl = $sce.trustAsResourceUrl($scope.currentProject.url);
    console.log( $scope.currentProject );
    console.log( $scope.currentProjectUrl );

}

这似乎解决了我的问题，尽管我不太清楚为什么.