核心数据搜索二级对象（项目类别）
我的核心数据系统使用具有单个类别集的项目（例如 item.category =
目前发送搜索字符串“string”将仅匹配包含该字符串的项目，但我希望类别也匹配。是否可以设置一个使用此嵌套结构或自定义选择器的 NSPredicate 来告诉系统搜索字符串是否匹配？
在伪代码中，这就是我正在寻找的内容：
if (item.title contains "search string" OR item.category.title contains "search string")
object matches search string
My core data system uses items that have a single category set (for example item.category = <Category object>) and I want to use my NSPredicate to search through them.
Currently sending a search string "string" will only match items that contain that string, but I want categories to match as well. Is it possible to set up an NSPredicate that uses this nested structure or a custom selector to tell the system if the search string matches?
In pseudo-code, here is what I'm looking for:
if (item.title contains "search string" OR item.category.title contains "search string")
object matches search string
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是的，KVC（键值编码）允许您通过实体进行任意深度的链接。但是请注意，连接在一起的实体越多，谓词的成本就越高：
这是假设您正在针对“item”实体表运行谓词。
Yes, KVC (Key Value Coding) allows you to chain as deep as you want through entities. However be warned that the predicate gets more expensive the more entities you join together:
This is assuming you are running the predicate against the "item" entity table.