AngularJS directive for a user agreement view, detect enabling button, does not work on mobile safari

Question

I have a user agreement screen. Basically a HTML view with an iframe and a button. I want to enable the button when the user scrolls to the bottom. This works for all desktop browsers, IE, Chrome, Safari but doesn't work on mobile safari or chrome on ios devices. It seems that the 'scrolling' event doesn't get attached properly. Do you see something here that would make that work?

(function() {
  angular.module('myapp').directive('textAgreement', function($timeout, ActivityLogService) {
    return {
      restrict: 'A',          
      scope: {
        onscrollCallback: '&onscrollCallback',
        onloadCallback: '&onloadCallback'
      },
      compile: function(tElement) {        
        return function(scope, element) {
          /** Called on load **/
          var appliedCheck = function(event) {
            try {
              if (typeof scope.onloadCallback !== undefined) {
                if (typeof scope.onloadCallback == 'function') {                      
                  scope.onloadCallback();  
                  scope.$apply();
                }
              } 
              var elm = element[0].contentWindow.document.body;
              var newwin = element[0].contentWindow;            
              if (elm) {
                $(newwin).scroll(function() {
                  var checkBottom = (elm.scrollTop+600) >= elm.scrollHeight;
                  console.log('###$$$ +++++ ' + elm.scrollTop +  ' ' + elm.scrollHeight);                                   
                  if (checkBottom) {        
                    scope.bottom = true;
                    if (typeof scope.onscrollCallback !== undefined) {
                      if (typeof scope.onscrollCallback == 'function') {                      
                        scope.onscrollCallback();  
                        scope.$apply();
                      }
                    }                  
                  }
                });                
              }
            } catch(e) {
              console.log(e);              
            }
          }; 
          element.bind('load', appliedCheck);                                    
        }; 
      }    
    };
  });   
})();

            <iframe text-agreement onload-callback="disableLoading()" onscroll-callback="enableAgree()" id="agreeFrame" src="{{ ::trustSrcAgreementUri }}" style="border:0" width="100%" height="100%"></iframe>

Answer 1

Scroll events don't work on mobile as they work on the desktop. In essence, the scroll event is only fired at the end of the scroll. See this:

http://andyshora.com/mobile-scroll-event-problems.html