iOS how to create NSPredicate with custom object key?

Question

I'm building a game and have a spell class. Within this class there's a list of active instances of this spell. I'm trying to check if this spell has already been cast on some target by using a predicate: target == %@ . However, the code below does not return any objects.

How can I check if a key is equal to a custom object within a predicate?

   -(BOOL)checkHasUniqueInstanceWithModel:(CharacterModelNode*)targetModel
    {
        NSPredicate *uniqueSkillInstancePredicate =
 [NSPredicate predicateWithFormat:@"target == %@", targetModel];



        NSArray *results = [self.activeInstances filteredArrayUsingPredicate:uniqueSkillInstancePredicate];

        if(results.count == 0)
        {
            return NO;
        }else if(results.count == 1)
        {
            return YES;
        }else
        {
            NSAssert(false,@"Duplicate unique instance with skill: %@ on target: %@",self.name,targetModel.character.name);
        }
        return NO;
    }

found that the predicate was correct, I was simply comparing it to a wrong object. — Alex Stone
– Alex Stone, Commented Jan 25, 2014 at 1:29

Alex Stone · Accepted Answer · 2014-01-25 01:31:05Z

1

Use a predicate with block:

NSPredicate *pred = [NSPredicate predicateWithBlock:^BOOL(Spell* evaluatedObject, NSDictionary *bindings) {
    if([evaluatedObject.target isEqual: targetModel])
    {
        return true;
    }
    return false;
}];

NSArray *results = [self.activeInstances filteredArrayUsingPredicate:pred ];

edited Jan 25, 2014 at 1:31

Alex Stone

47.4k59 gold badges240 silver badges422 bronze badges

answered Jan 25, 2014 at 1:25

Putz1103

6,2011 gold badge21 silver badges27 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

iOS how to create NSPredicate with custom object key?

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related