CloudKit复合查询（使用OR查询） [英] CloudKit compound query (query with OR)

问题描述

我想使用带有两个字段的OR来​​查询CloudKit。但我找不到办法如何做到这一点。我做的是：

I would like to query CloudKit using OR with two fields. But I can't find a way how to do this. What I did is:

NSPredicate *predicate1 = [NSPredicate predicateWithFormat:@"(creatorUserRecordID == %@)", userId];
NSPredicate *predicate2 = [NSPredicate predicateWithFormat:@"(toUser == %@)", userId];
NSCompoundPredicate *compPredicate = [NSCompoundPredicate orPredicateWithSubpredicates:@[predicate1, predicate2]];
CKQuery *query = [[CKQuery alloc] initWithRecordType:@"Message" predicate:compPredicate];

但遗憾的是CKQuery不支持OR查询（如文档中所述）我能否实现其他一些效果方式？

But unfortunately CKQuery does not support OR query (as written in documentation) Can I achieve this effect some other way?

推荐答案

CKQuery支持AND和NOT，所以你可以想象你可以使用简单的布尔代数来创建一个基于事实上，NOT（不是A而不是B）== A或B.但是，文档明确说明：

CKQuery supports AND and NOT, so you would imagine you could use simple boolean algebra to create a query based on the fact that NOT(NOT A AND NOT B) == A OR B. HOWEVER, the documentation specifically says:

在以下情况下不支持NOT复合运算符：

"The NOT compound operator is not supported in the following cases:

你不能用它来否定AND复合谓词。

You cannot use it to negate an AND compound predicate."

所以你必须分别查询每个ORed谓词，将它们作为SET保存，然后取两个集合的交集来得到最终结果

So you must query for each of the ORed predicates separately save them each as a SET and then take the intersection of the two sets to get the final result

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