saving, deleting and fetching data from a one to many relationship core data

Question

I have created a data model like so:

I have this code for a fetch request:

func roundFetchRequest() -> NSFetchRequest {
    let fetchRequest = NSFetchRequest(entityName: "Customer")
    print("Check here: \(myRoundIndexPath)")
    //let predicate : NSPredicate = NSPredicate(format: "custRoundRel = %@", frc2.objectAtIndexPath(myRoundIndexPath!) as! RoundName) //ASSUME THIS IS CORRECT
    let sortDescriptor = NSSortDescriptor(key: "c2fna", ascending: true)
    //fetchRequest.predicate = predicate
    fetchRequest.sortDescriptors = [sortDescriptor]
    return fetchRequest
}

My commented out code does not give an error, but I cannot seem to save a customer to the RoundName instance. When I save a customer with its attributes, I have used this code:

func newCust() {
    let cont = self.context
    let newCustomer = NSEntityDescription.entityForName("Customer", inManagedObjectContext: cont)
    let aCust = Customer(entity: newCustomer!, insertIntoManagedObjectContext: cont)

    aCust.c2fna = firstName.text
    aCust.c3lna = lastName.text
    aCust.c4tel = tel.text
    aCust.c5mob = mob.text
    aCust.c6ema = email.text
    aCust.c7hsn = houseNo.text
    aCust.c8fir = street.text
    aCust.c9sec = secondLine.text
    aCust.c10ar = area.text
    aCust.c11pc = postcode.text
    aCust.c12cos = cost.text
    aCust.c13fq = frequencyNumber.text
    aCust.c14fqt = frequencyType.text
    let DF = NSDateFormatter()
    aCust.c15das = DF.dateFromString(startDate.text!)
    //Do Pics in a minute & next date in a minute
    aCust.c17notes = notes.text

    //print("Desc = \(picRound.image?.description)")

    do {
        try context.save()
        print("Save Successful")
    } catch {
        print("Save Unsuccessful")
    }
}

What is the code to link this customer with the correct Round?

Thanks, I am very new to core data and really would appreciate any help.

Answer 1

Yes, you use a predicate on your fetch request, with a format like

NSPredicate(format:"custRoundRel = %@", xxxx) 

where xxxx is the Round instance.

You can also just use the roundCustRel relationship depending on what you want to do with the Customer instances and how many there are.