Core Data Predicate To Many

Posted by Vikings on Stack Overflow See other posts from Stack Overflow or by Vikings
Published on 2012-10-31T22:35:50Z Indexed on 2012/10/31 23:00 UTC
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I have a core data model that has a one to many relationship, there is a category, and it can contain many subcategories.

Category <---->> Subcategory

I am trying to perform a fetch that checks if a particular Category contains a Subcategory with a particular name. Let's say I have two categories below, I want to fetch to see if there are any subcategories name "Apple" in the Category named "Fruits".

 Vetegables
    - Carrot
    - Lettuce

 Fruits
    - Apple
    - Orange
    - Pear

Code:

- (SubCategory *)searchForSubCategoryWithName:(NSString *)subCategory
                                   inCategory:(Category *)category
{
    NSFetchRequest *fetchRequest = [[NSFetchRequest alloc] init];
    NSEntityDescription *entity = [NSEntityDescription entityForName:@"SubCategory" inManagedObjectContext:self.beer.managedObjectContext];
    [fetchRequest setEntity:entity];

    NSPredicate *predicate = [NSPredicate predicateWithFormat:@"name == [c] %@", subCategory];
    [fetchRequest setPredicate:predicate];

    NSError *error;
    NSArray *fetchedObjects = [self.beer.managedObjectContext executeFetchRequest:fetchRequest error:&error];

    if (fetchedObjects != nil && fetchedObjects.count > 0) {
        return [fetchedObjects objectAtIndex:0];
    }
    else {
        return nil;
    }
}

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