How to enable smooth scrolling on mobile iOs?

Unfortunately Smooth Scrolling is not possible in Safari on OSX and iOS natively. But there are some JavaScript polyfills for that. For example: https://github.com/iamdustan/smoothscroll You have to initialize it with JavaScript, not with CSS.

Using jQuery you can do like this:

<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.5.1/jquery.min.js"></script>

JS

$(document).ready(function(){
  // Add smooth scrolling to all links with the class scroll
  $("a.scroll").on('click', function(event) {

    // Make sure this.hash has a value before overriding default behavior
    if (this.hash !== "") {
      // Prevent default anchor click behavior
      event.preventDefault();

      // Store hash
      var hash = this.hash;

      // Using jQuery's animate() method to add smooth page scroll
      // The optional number (800) specifies the number of milliseconds it takes to scroll to the specified area
      $('html, body').animate({
        scrollTop: $(hash).offset().top
      }, 800, function(){

        // Add hash (#) to URL when done scrolling (default click behavior)
        window.location.hash = hash;
      });
    } // End if
  });
});

HTML

<a class="scroll" href="#">Text</a>

So i solved this problem with smoothscroll-polyfill, this is enable to scroll my page smoothly on mobile ios

For anyone who wants to customize/enhance the smooth-scrolling with support for basically any modern browser (Safari/Safari for iOS included) you can take a look at this API I wrote.
Compared to the standard polyfill it allows to use custom ease functions, smooth-scrolling multiple elements at the same time, interrupting the scrolling-animations and more on both the x and y axises.
You can find more about it here.

Use the next CDN for a pollyfill.

<script src="https://cdnjs.cloudflare.com/ajax/libs/iamdustan-smoothscroll/0.4.0/smoothscroll.min.js"></script>