调用ios原生的Photos框架

var PHPhotoLibrary = plus.ios.importClass("PHPhotoLibrary");
var authStatus = PHPhotoLibrary.authorizationStatus();
if(authStatus == 3)
{
var FetchOptions = plus.ios.importClass("PHFetchOptions");
var fetchOptions = new FetchOptions();
var PHAsset = plus.ios.importClass("PHAsset");
var imageList = PHAsset.fetchAssetsWithMediaTypeoptions(1,fetchOptions);
var jsonData = JSON.stringify(imageList);
｝
为什么这个返回的imageList不是图片列表