Handling duplicate entries in Core Data

Question

I have an app that allows users to save favorites. I am using Core Data to store the favorites as managed objects. I have written some code to prevent the possibility of storing

Answer 1

Swift 3:

func isExist(id: Int) -> Bool {
    let fetchRequest = NSFetchRequest(entityName: myEntityName)
    fetchRequest.predicate = NSPredicate(format: "id = %d", argumentArray: id)

    let res = try! theContext.fetch(fetchRequest)
    return res.count > 0 ? true : false
}