如何解决 NSPredicate 错误“不能将 in/contains 运算符与集合 8(不是集合)一起使用" [英] how to solve NSPredicate error 'Can't use in/contains operator with collection 8 (not a collection)

问题描述

我尝试根据初始查询的情绪来预测我的核心日期，所有情绪都设置为 8.我将每秒钟从 0 - 7 调用一次以更新 tableview.

I tried to predicate my coredate based on the mood on the initial queries all the moods are set to 8. I will be calling from 0 - 7 every sec to update the tableview.

但是我得到了

Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: 'Can't use in/contains operator with collection 8 (not a collection)'

我应该使用 CONTAINS 或其他运算符来做谓词吗?

Should I use CONTAINS or other operator to predicate?

NSString* filter = @"%K CONTAINS[cd] %@";
NSPredicate *getMoodPred = [NSPredicate predicateWithFormat:filter, @"mood", mood];
NSLog(@"getmood %@",getMoodPred); //getmood mood CONTAINS[cd] "7"
NSArray *getMoodArray = [[VPPCoreData sharedInstance]allObjectsForEntity:@"Song" orderBy:Nil filteredBy:getMoodPred];

推荐答案

这可能意味着 mood 属性存储为 Number，而不是 String.CONTAINS"仅适用于字符串.以下谓词应该有效:

The probably means that the mood attribute is stored as Number, not as String. "CONTAINS" works only with strings. The following predicate should work:

NSNumber *mood = @(7);
NSString *filter = @"%K == %@";
NSPredicate *getMoodPred = [NSPredicate predicateWithFormat:filter, @"mood", mood];

在 rhs 上使用 NSNumber 和 == 作为比较器.

using NSNumber on the rhs and == as comparator.

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