let fetchRequest = NSFetchRequest(entityName: "Person")
// Use NSPredicate like bellow
fetchRequest.predicate = NSPredicate(format: "age == %@", "25")
do {
    let results = try context.fetch(fetchRequest)
    for result in results as! [NSManagedObject] {
        print(result.valueForKey("name") as! String)
    }
} catch let error as NSError {
    print("Could not fetch \(error), \(error.userInfo)")
}