class Login_item: Object {
dynamic var username = String()
dynamic var password = String()

override static func primaryKey() -> String? {
    return "username"
}

func save_login_info() {
    let new_login_entry = Login_item()

    new_login_entry.username = Username.text!
    new_login_entry.password = Password.text!

    let realm = try! Realm()
    try! realm.write {
        realm.add(new_login_entry)
        print("Login info save as: (Realm.Configuration.defaultConfiguration.fileURL!)")
    }

    try! realm.write {
        realm.add(new_login_entry, update: true)
    }
}

let config = Realm.Configuration(schemaVersion: 1, migrationBlock: { migration, oldSchemaVersion in
  if oldSchemaVersion < 1 {

  }
})