Obj-C - Filter NSMutableArray with another array?

Question

I have an NSMutableArray (self.allPeople) containing a number of dictionaries (people). That said, I also have an NSMutableArray (self.participants) that contains a series of numbers:

self.participants

Here they are: (
    179,
    125,
    231
)

I want filter self.allPeople, and only return dictionaries in which the key "nid" is equal to one of the numbers contained in self.participants.

How can I filter self.allPeople (valueForKey:@"nid") with each number in self.participants?

This works if I only want to filter by a single string value, but I need it to filter for all numbers:

  NSPredicate *p = [NSPredicate predicateWithFormat:@"nid CONTAINS[cd] %@", @"179"];
  self.results = [self.allPeople filteredArrayUsingPredicate:p];

Eugene Dudnyk · Accepted Answer · 2021-08-15 20:36:55Z

1

Just use IN for the array, like this:

NSArray<NSDictionary<NSString *, NSNumber *> *> *allPeople = @[
    @{ @"nid": @120 },
    @{ @"nid": @121 },
    @{ @"nid": @122 },
    @{ @"nid": @123 },
];
NSArray<NSNumber *> *participants = @[ @120, @123 ];
NSPredicate *predicate = [NSPredicate predicateWithFormat:@"nid IN %@", participants];
NSArray<NSDictionary<NSString *, NSNumber *> *> *results = [allPeople filteredArrayUsingPredicate:predicate];
NSLog(@"RESULTS: %@", results);

answered Aug 15, 2021 at 20:36

Eugene Dudnyk

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