Can I use sendBeacon to save session duration metric real-time in iOS devices?

I have integrated the timeonsite library to store the time users spend on the site in a MySQL database. I’m using the following code to achieve the same.

However, the data is not getting stored in IOS devices like iPhone or iPad but works in all other browsers like Chrome, Edge, Opera, Firefox, etc. including Android chrome and firefox.

var Tos;
(function(d, s, id, file) {
  var js, fjs = d.getElementsByTagName(s)[0];
  if (d.getElementById(id)) return;
  js = d.createElement(s);
  js.id = id;
  js.onload = function() {

    var config = {
      trackBy: 'seconds',
      callback: function(data) {
        console.log(data);
        // give your endpoint URL server-side URL
        // that is going to handle your TOS data which is of POST method.
        // Eg. PHP, nodejs or python URL which saves this data to your DB

        // replace with your endpoint URL
        var endPointUrl="http://localhost:4500/tos";

        if (data && data.trackingType) {
          if (data.trackingType == 'tos') {
            if (Tos.verifyData(data) != 'valid') {
              console.log('Data abolished!');
              return;
            }
          }

          // make use of sendBeacon if this API is supported by your browser.
          // sendBeacon is experimental technology; it may not work well
          if (navigator && typeof navigator.sendBeacon === 'function') {
            var blob = new Blob([JSON.stringify(data)], {
              type: 'application/json'
            });
            navigator.sendBeacon(endPointUrl, blob);
          }

        }
      }
    };

    if (TimeOnSiteTracker) {
      Tos = new TimeOnSiteTracker(config);
    }
  };
  js.src = file;
  fjs.parentNode.insertBefore(js, fjs);
}(document, 'script', 'TimeOnSiteTracker', 'https://cdnjs.cloudflare.com/ajax/libs/timeonsite/1.2.0/timeonsitetracker.js'));

What’s the reason for this issue and how to get it resolved?