没有排序描述符的NSFetchRequest [英] NSFetchRequest without sort descriptors
问题描述
我们不能在不提供NSSortDescriptor的情况下使用NSFetchRequest。我想要做的就是获取结果并按照创建顺序显示它们。有内置的方法吗?或者我是否必须创建一个新的自动增量字段? (在我看来,这与CoreData所代表的一切相悖)。
We cannot use NSFetchRequest without providing NSSortDescriptor(s). All i want to do is fetch the results and show them in the order in which they were created. Is there a built-in way to do that?, or will i have to create a new "auto-increment" field? (which goes against everything CoreData stands for, in my opinion).
推荐答案
核心数据不保证订单的任何内容。您不必进行自动增量字段;但是,您可以创建适当的属性。由于您显然关心创建日期,因此应将dateCreated属性添加到数据对象中。然后,按此排序。
Core Data does not guarantee anything about order. You don't have to make an "auto-increment" field; however, you can make an appropriate attribute. Since you obviously care about the date something was created, you should add a dateCreated attribute to your data object. Then, sort by that.
您可以在托管对象的 didAwakeFromInsert
方法中轻松设置它。
You can easily set that in the managed object's didAwakeFromInsert
method.
这篇关于没有排序描述符的NSFetchRequest的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!