How to set selected values to ListBox

I checked with the debugger the content of the MultiSelectList values have changed. So I saw that after the values of which are chosen selected Value = true;.

But I did not see in my view. When was run, selected value not visible. Lastly I tried ViewBag, ViewData, ListBox() and few couple things more. I don't see what?

This is my Controller:

public ActionResult Edit(int id)
        {
            UserDto user = _userService.GetUserById(id);

            var companiesSelectList = new MultiSelectList(_companyService.GetCompanies(), "Id", "Name", user.Companies.Select(x => x.Id.ToString()).ToArray());


            TempData["CompaniesList"] = companiesSelectList;
            return View(user);
        }

And my View:

 <div class="col-md-10">
    @Html.ListBoxFor(model => model.Companies, (MultiSelectList)TempData["CompaniesList"], new { @class = "form-control", @required = "required", @multiple = "multiple" })
            </div>

and I used this one for Visualisation

   $(document).ready(function () {

        $('#Companies').select2({

            placeholder: 'Please Select Company',
            maximumSelectionSize: 15,
            width: 400,
        });
    });

My friend fix it.

I got selected items in companiesSelectList but I dont set selected values. I need it JQuery like that. First:

   public JsonResult UserCompany(string userId)
        {
            UserDto user = _userService.GetUserById(int.Parse(userId));
            return Json(user.Companies.Select(x => x.Id).ToList(), JsonRequestBehavior.AllowGet);
        }

Json data carries Companies in which the user is connected I have sent companies Ids.

This Ajax Method Checking selected items:

 var userId = $('#Id').val();
    $.ajax({
        url: "/User/UserCompany",
        type: 'POST',
        data: { 'userId': userId },
        datatype: 'json',
        success: function (data) {
            $('#Companies').val(data).trigger("change");
        }

    });

thanks my work friend and whoever is looked at my question. c u another question :)