需要帮助。我的表中有4个字段:电子邮件留言阅读date_received我要选择email,message(recent),date_received,andunreadmessages这是我的预期结果:测试@email.com|测试留言|2015-02-27|28test2@email.com|测试消息2|2015-02-29|2这是我当前的代码:letfetchRequest:NSFetchRequest=NSFetchRequest()ifletentityDescription:NSEntityDescription=NSEntityDescription.entityForN