Hi Timo,
I've found something more like ActiveRecord; it's a framework https://github.com/magicalpanda/MagicalRecord!
everything is written in Objective-C, but you can use it with MacRuby! you get syntax like:
person = Person...;
MRCoreDataAction.saveDataInBackgroundWithBlock -> localContext do
localPerson = person.inContext localContext
localPerson.firstName = "Chuck"
localPerson.lastName = "Smith"
end
but nevertheless, you should try to understand how CoreData really work!
Mateus
greetings from Köln