核心数据NSPredicate按实体类过滤？ [英] Core Data NSPredicate filter by entity class?

问题描述

如何创建 NSPredicate 以按类联系人？实体过滤？

对 NSPredicate检查类对象类的解决方案崩溃：

  [NSPredicate predicateWithFormat：@person.class ==％@，[Contact class]]; 
 
 ***由于未捕获异常而终止应用程序'NSInvalidArgumentException'，
原因：'keypath person.class在实体中找不到< NSSQLEntity User id = 12>'
  
 
 
 
背景
 
 
 
我有Core Data实体 User （app user）& 联系（地址簿联系人）， Person （抽象实体）的孩子。 人有许多身份，可以是电子邮件 code>电话或用户名。
 
 
 
我想为 Identity 创建 NSFetchRequest 实体，其中 person 是类别 c 
。
解决方案
也许混合了几件事情。你指出的答案是关于一个谓词，以筛选 UIView 的anrray。 
 
 
 
要实现所需的结果，只需设置实体您的撷取要求至 @联络人。
 
How would I create an NSPredicate to filter by entity of class Contact?

The solution to NSPredicate check for kind of object class crashes:
[NSPredicate predicateWithFormat:@"person.class == %@", [Contact class]];

*** Terminating app due to uncaught exception 'NSInvalidArgumentException',
    reason: 'keypath person.class not found in entity <NSSQLEntity User id=12>'


Background

I have the Core Data entities User (app user) & Contact (address book contact), both children of Person (abstract entity). Person has many identities, which can be emails, phones, or usernames.

To create a text-message-like typeahead, I want to create an NSFetchRequest for Identity entities where person is of class Contact.
解决方案
You are perhaps mixing up a few things. The answer you indicate is about a predicate to filter anrray of UIViews. A predicate in core data works in a slightly different way.

To achieve your desired result, simply set the entity of your fetch request to @"Contact".

                        
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