Creating a unique id for a Core Data program on the iPhone

Question

I am having a bit of trouble figuring out this Core Data stuff. How do I create a new entry with a unique ID? In SQL I would just declare one field as an autoincrement fie

Answer 1

Update to @Lukasz answer in Swift:

static func nextAvailble(_ idKey: String, forEntityName entityName: String, inContext context: NSManagedObjectContext) -> Int {
    let fetchRequest: NSFetchRequest = NSFetchRequest(entityName: entityName)
    fetchRequest.propertiesToFetch = [idKey]
    fetchRequest.sortDescriptors = [NSSortDescriptor(key: idKey, ascending: true)]

    do {
        let results = try context.fetch(fetchRequest)
        let lastObject = (results as! [NSManagedObject]).last

        guard lastObject != nil else {
            return 1
        }

        return lastObject?.value(forKey: idKey) as! Int + 1

    } catch let error as NSError {
        //handle error
    }

    return 1 
}