Parse.com has changed their syntax for relational data!

its almost exactly the same. instead of relationforKey you use relationForKey.

go to the relational data section under objects of the documentation here. scroll down until you see the part that mentions relations. it states:

You can also model a many-to-many relation using the PFRelation object. This works similar to an NSArray of PFObjects, except that you don't need to download all the Objects in a relation at once. This allows PFRelation to scale to many more objects than the NSArray of PFObject approach. For example, a User may have many Posts that they might like. In this case, you can store the set of Posts that a User likes using relationForKey:. In order to add a post to the list, the code would look something like

PFUser *user = [PFUser currentUser];
PFRelation *relation = [user relationForKey:@"likes"];
[relation addObject:post];
[user saveInBackground];

the code ben uses in the video to add an object to the relation is:

PFRelation *friendsRelation = [self.currentUser relationforKey@"friendsRelation"];
PFUser *user = [self.allUsers objectAtIndex:indexPath.row];
[friendsRelation addObject:user];

and then saves the user in the background. the only difference is the lower case f in relationforKey, this is has been deprecated and now the method is relationForKey