Unity/UniRx/モバイルキーボード取得

    private IObservable<TouchScreenKeyboard> touchScreenKeyboardOnDoneAsObservable;
    void Start()
    {
        touchScreenKeyboardOnDoneAsObservable = Observable.EveryUpdate()
            .Select(_ => TouchScreenKeyboard.Open("", TouchScreenKeyboardType.NamePhonePad, false, false, false))
            .Where(_ => _ != null)
            .Where(_ => TouchScreenKeyboard.isSupported)
            .Where(_ => _.status == TouchScreenKeyboard.Status.Done);

        touchScreenKeyboardOnDoneAsObservable
        .Subscribe(touchScreenKeyboard =>
            GameObject.Find("DebugText").GetComponent<Text>().text = touchScreenKeyboard.text
            // Debug.Log(touchScreenKeyboard.text)
        )
        .AddTo(gameObject);

DebugTextに表示されず・・。失敗