CODEWITHSUNDEEP
iosobjective-cnsarraynspredicate
sermilion
sermilion

Reputation: 185

Using NSPredicate to find elements in an NSArray similar to SQL WHERE IN clause

I have an NSArray of, say Article objects. Article object contains another NSArray of tags to the article. So I want to find articles that contain a set of tags like [iphone, apple, music]. In SQL it would be like: WHERE tags IN ('iphone', 'apple', 'music'). So far I have only found how to use NSPredicate to finds elements by single value:

NSArray *filteredItems = [article filteredArrayUsingPredicate:
                                       [NSPredicate predicateWithFormat:@"tag == %@", @"iphone"]];

Is there a way to do what I need to?

Upvotes: 0

Views: 485

Answers (4)

KerrM
KerrM

Reputation: 5240

You can use NSCompoundPredicate to merge together various NSPredicate objects like this:

NSMutableArray *predicates = [NSMutableArray array];

[predicates addObject:[NSPredicate predicateWithFormat:@"tag == %@", @"iphone"]]];
[predicates addObject:[NSPredicate predicateWithFormat:@"tag == %@", @"apple"]]];
[predicates addObject:[NSPredicate predicateWithFormat:@"tag == %@", @"music"]]];

//Create a predicate using AND
NSPredicate *compoundANDpred = [NSCompoundPredicate andPredicateWithSubpredicates:predicates];

//Create a predicate using OR
NSPredicate *compoundORpred = [NSCompoundPredicate orPredicateWithSubpredicates:predicates];

or you could use a predicate with ANY and IN, as outlined in some of the other answers.

Upvotes: 1

user1101733
user1101733

Reputation: 258

This can also be done like this

NSPredicate *predicate = [NSPredicate predicateWithFormat:@"tag == %@", @[@"iphone", @"apple", @"music"]];
NSArray *result = [dataArray filterUsingPredicate:predicate];

Upvotes: 0

sidslog
sidslog

Reputation: 654

You can use ANY and IN clause

NSArray *tags = ...; [NSPredicate predicateWithFormat:@"ANY tags.name IN %@",tags]

Upvotes: 2

Chetan
Chetan

Reputation: 2124

You wan use the predicate like below

NSPredicate *template = [NSPredicate predicateWithFormat:@"tag == %@ OR tag == %@ OR tag == %@",@"iphone",@"apple",@"music"];

Upvotes: 0

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