Core Data traversing entities with an NSArrayController content set?

Question

I have 3 entities in a Core Data application:

Projeto <-->> Servico <-->> Sessao (the relationships are named as usual).

Projeto.servico (to many Projeto --> Servico)

Servico.projeto (inverse to one Servico --> Projeto)

Servico.sessaoDoServico (to many Servico --> Sessao)

Sessao.servicoDaSessao (inverse to one Sessao --> Servico)

Each entity is connected to an array controller, like "Department and employees" in Apple Docs. It's Working fine in a typical Master - details configuration.

Now I want to have all Sessions from a selected Project. (I don't have a relationship between Sessao and Projeto)

I'm trying to bind the SessionArrayController Content Set to filter the sessions without success.

How could I have all sessions for a selected project?

I created a property for the Session Class, returning a NSSet and I can print the desired sessions, but I have no idea, how I could do it with binding.

-(NSSet *)sessoesDoProjeto{
NSSet *allSessions = [self.projeto.servico valueForKey:@"sessaoDoServico"];
NSLog(@"allSessions %@",allSessions);
return allSessions;
}

Could I create a NSArrayController with the above NSSet?

Any help would be appreciated

Answer 1

I found the solution, so I'm posting for others with the same problem.

I bound the Content Array (not content set) of the SessionArrayController to:

ServicoArrayController_by_Project.arrangedObjects.@unionOfSets.sessaoDoServico

It works like a charm!