Compare object properties in different arrays (objective-c)

Question

I have an array of current animal objects that can be viewed by day - for example, monday will return all animals that are available on a monday, etc.

I also have an array of saved animal objects.

How do I ensure that the saved animals don't show up in the current animals list?

Something like, if the currentAnimal.name isEqual to savedAnimal.name?

I need the objects in both arrays so it is important to compare the .name properties, I think?

Simon Lee · Accepted Answer · 2011-06-20 12:58:02Z

4

Override isEqual and hash to do a comparison on the name if that is what you consider to make the objects 'equal'.

- (BOOL)isEqual:(id)other {
    if (other == self)
        return YES;
    if (!other || ![other isKindOfClass:[self class]])
        return NO;
    return [((MyObject *)other).name isEqualToString:name];
}

and

- (NSUInteger)hash {
  return [name hash];
}

answered Jun 20, 2011 at 12:58

Simon Lee

22.3k4 gold badges43 silver badges45 bronze badges

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

4 Comments

medley Over a year ago

Thanks for your answer but I'm not getting this at all, and I don't even know what hash is. What's 'other' and what's 'self', and where are the arrays?

Simon Lee Over a year ago

hash and isEqual are default methods that Objective-c use to test the equality of an object. Normally these do instance equality, i.e. if the objects are the same instance, however you are saying that you may have two different instances BUT if the name is the same then you consider them equal. By overriding the methods you can redefine what it means for the object to be equal. The runtime will call these methods automatically so you just need to implement them... other is passed to the method, all you are doing is doing the equality check on the name.

medley Over a year ago

OK, thanks for that, I understand better now. I think the problem I'm having now is getting the reference to the object from the saved array into this method. Hopefully this will work!!!

Simon Lee Over a year ago

If you implement these methods, then you can either do [myobject1 isEqual:myobject2] to see if they are equal OR if(![myarray containsObject:myobject]) { [myarray addObject:myobject]; }

gsempe · Accepted Answer · 2011-06-20 13:02:58Z

0

You should use isEqual method if you want objects strictly equals or method isKindOfClass. Look at NSObject reference

answered Jun 20, 2011 at 13:02

gsempe

5,5392 gold badges29 silver badges29 bronze badges

2 Comments

medley Over a year ago

I don't want strictly equals though do I? I only want one of the Objects properties to match, not all of them.

gsempe Over a year ago

@Simon give you the exact answer you need.

Collectives™ on Stack Overflow

Compare object properties in different arrays (objective-c)

2 Answers 2

4 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

4 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related