test

rx.swift

var states: Variable<[String]> = Variable([])
    states.asObservable()
    .filter({ (array) -> Bool in
      var valid: Bool = true
      for x in array {
        valid = x.characters.count > 3
      }
      print(valid)
      return valid
    }).subscribe(onNext: { _ in
      print("init")
    }).addDisposableTo(DisposeBag())

    let name = nameTextField.rx.text
    name.subscribe(onNext: { (string) in
      states.value.append((string as! String?)!)
    })