How do I add a pop-up message to timer question on offline app?

So I added the code below to the timer question (original code from AnthonyR). It works BEAUTIFULLY if I run the survey online through my browser. The problem is that we will be collecting data from 1000s of kids through the Qualtrics App offline (since not all schools have access to the internet). I can't get the pop-up message to work when I run the survey through the app. Is there a way I can get this to work? We're trying to avoid using hand-held timers that can be really noisy and disruptive in classrooms.

Thank you for your time!

Qualtrics.SurveyEngine.addOnReady(function()
{
setTimeout(function(){
  alert("60 seconds are up!");
}, 60000); //60000 ms is 60 seconds or 1 minute

});