CloudKit - 用于在引用列表中查找包含指定CKReference的所有记录的NSPredicate [英] CloudKit - NSPredicate for finding all records that contain specified CKReference in a reference list

问题描述

我正在使用具有跟随引用列表属性的用户记录类型的CloudKit支持的应用程序。我正在尝试构建一个查询以获取跟随指定用户的每个用户（即指定用户在以下参考列表中显示为条目的那些用户）。

<我正在尝试为 CKQuery 构建我的 NSPredicate ：

  NSPredicate * predicate = [NSPredicate predicateWithFormat：@％@ IN follow，[[CKReference alloc] initWithRecordID：currentUserID action：CKReferenceActionNone]]; 
 CKQuery * query = [[CKQuery alloc] initWithRecordType：UserRecordType predicate：predicate]; 
  

并且CloudKit返回以下错误消息：

 未知物品（11/2003）; server message =未找到所需的记录类型; 
  

我觉得我的谓词中可能会遗漏一些相当简单的东西。任何帮助将不胜感激！

解决方案

使用CONTAINS运算符测试列表成员资格：

  CKReference * recordToMatch = [[CKReference alloc] initWithRecordID：currentUserID action：CKReferenceActionNone]; 
 NSPredicate * predicate = [NSPredicate predicateWithFormat：@跟随CONTAINS％@，recordToMatch]; 
  

如果要查询多个引用，则需要使用带有AND的复合谓词列表中每个引用的谓词类型。

I am working on a CloudKit backed app with a Users record type that has a "following" reference list attribute. I am trying to construct a query to get every user that is following a specified user (i.e. those users in which the specified user appears as an entry in the following reference list).

I am currently trying to construct my NSPredicate for the CKQuery as such:

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"%@ IN following", [[CKReference alloc] initWithRecordID:currentUserID action:CKReferenceActionNone]];
CKQuery *query = [[CKQuery alloc] initWithRecordType:UserRecordType predicate:predicate];

And CloudKit returns the following error message:

"Unknown Item" (11/2003); server message = "did not find required record type";

I feel I might be missing something pretty straight forward in my predicate. Any help would be greatly appreciated!

解决方案

Use CONTAINS operator to test list membership:

CKReference* recordToMatch = [[CKReference alloc] initWithRecordID:currentUserID action:CKReferenceActionNone];
NSPredicate* predicate = [NSPredicate predicateWithFormat:@"following CONTAINS %@", recordToMatch];

If you want to query for more than 1 reference, then you need to use a compound predicate with AND predicate type for each reference in list.

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