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 4 Curled from @Vahid answer

func isEntityAttributeExist(id: Int, entityName: String) -> Bool {
    let appDelegate = UIApplication.shared.delegate as! AppDelegate
    let managedContext = appDelegate.persistentContainer.viewContext
    let fetchRequest = NSFetchRequest(entityName: entityName)
    fetchRequest.predicate = NSPredicate(format: "id == %@", id)
    let res = try! managedContext.fetch(fetchRequest)
    return res.count > 0 ? true : false
}