SWIFT: Next ID for CoreData row

app.swift

var appDelegate = UIApplication.sharedApplication().delegate as AppDelegate
var context = appDelegate.managedObjectContext
var request = NSFetchRequest(entityName: "Entity")

request.fetchLimit = 1
request.sortDescriptors = [NSSortDescriptor(key: "id", ascending: false)]

var error: NSError? = nil
let entities = context.executeFetchRequest(request, error: &error) as [Entity]

var nextId = entities.isEmpty ? 1 : (entities[0].id + 1)