我的照片扩展应用程序可以访问相机和照片。一切正常，但按完成时，无法保存图像。标准完成处理程序代码:-(void)finishContentEditingWithCompletionHandler:(void(^)(PHContentEditingOutput*))completionHandler{//UpdateUItoreflectthateditinghasfinishedandoutputisbeingrendered.//Renderandprovideoutputonabackgroundqueue.dispatch_async(dispatch_get_global_qu