I have one to many objects `Driver <-->> Car`.  

Classes:

```
class Driver: NSManagedObject {
   @NSManaged var fullName: String
    @NSManaged var cars: NSSet
}
class Car: NSManagedObject {
   @NSManaged var model: String
   @NSManaged var year: String
   @NSManaged var driver: Driver
}

```

I inserted one Driver and a few car objects.  

But I don't know what is the proper way to update car list to add or remove some car object.  

Wired but I can't find any example on net how to do this.  

So how to just add new car to existing driver or remove car from it?  

**UPDATE**
I tried something like this but it saves new car in database but those new cars are not related to driver.  

When I fetch driver in `cars:NSSet` I am still getting one car.

```
let context = (UIApplication.sharedApplication().delegate as! AppDelegate).managedObjectContext;

        var newCar:Car = NSEntityDescription.insertNewObjectForEntityForName("Car", inManagedObjectContext: context!) as! Car

        newCar.year = "1977";

        var cars = driver?.cars.allObjects as! [Car]

        cars.append(newCar)

        var err: NSError?;

        context?.save(&err);

```