Swift set or update asset in core data - core-data

Question

Two Entities
Gymnast is one to many to Meet
I would like to when I save a new meet, it gets assigned to as a meet to each gymnast where they can then score their individuals scores for each event
Maybe I completely wrong in my logic, but here is what I am trying to do
let request = NSFetchRequest(entityName: "Gymnast")
do {
let entities = try AD.managedObjectContext.executeFetchRequest(request) as! [Gymnast]
for item in entities {
if let first = item.valueForKey("firstName"), last = item.valueForKey("lastName") {
print("Name: \(first) \(last)")
let myMeet = NSEntityDescription.insertNewObjectForEntityForName("Meet", inManagedObjectContext: AD.managedObjectContext) as! Meet
myMeet.meetName = "Winter Classic"
let myMeets = item.meets!.mutableCopy() as! NSMutableSet
myMeets.addObject(myMeet)
item.meets = myMeets.copy() as? NSSet
AD.saveContext()
}
}
} catch {
}
}
}

Answer 1

I think it is not ideal to replicate the Meet object over and over again for each Gymnast. For example, the meetName will be stored multiple times. I am not sure this is intended.
However, going with your setup, your problem is how you assign the to-many relationship. For a one-to-many it is always easier to simply set the to-one relationship. (Remember, there is always a reverse relationship in the Core Data model.)
Thus,
myMeet.gymnast = item
is all you need.
To add and remove to-many relationships, you can use this extension:
// Support adding to many-to-many relationships
extension NSManagedObject {
func addObject(value: NSManagedObject, forKey key: String) {
let items = self.mutableSetValueForKey(key)
items.addObject(value)
}
func removeObject(value: NSManagedObject, forKey key: String) {
let items = self.mutableSetValueForKey(key)
items.removeObject(value)
}
}