核心数据匹配一个到许多关系到列表 [英] Core Data match a to many relationship to a list

问题描述

相关于此问题，它发生了一个新的：

Related to this question, it occured a new one :

说我有这些属性： [red，green，blue] fetch对象的某些或所有属性都在列表中但仅在此列表中

Say I have these Attributes : [red, green, blue] How can I fetch objects whose some or all attributes are in list, but in this list only ?

* Object_1 (red, green, blue)
* Object_2 (red, green)
* Object_3 (red)

b $ b

这意味着不会获取 Object_4（红色，绿色，蓝色，黄色），因为它有黄色不在列表中

This means not fetch Object_4 (red, green, blue, yellow) because it has yellow which is not in the list

推荐答案

您可以创建一个复合谓词，可以添加您的3个谓词：

you can make a compound predicate which can add your 3 predicates :

NSPredicate *predOne = [NSPredicate predicateWithFormat:@"color == %@",@"red"];
NSPredicate *predTwo = [NSPredicate predicateWithFormat:@"color == %@",@"blue"];
NSPredicate *predThree = [NSPredicate predicateWithFormat:@"color == %@",@"green"];
NSArray *allPredicates = [[NSArray alloc] initWithObjects:predOne,predTwo,predThree, nil];
NSPredicate finalPredicate = [NSCompoundPredicate andPredicateWithSubpredicates:allPredicates];

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