Helper method for automatically returning a View or Json

BaseController.Helper.cs

protected ActionResult ViewOrJson(object model)
{
    return ViewOrJson(null, model);
}

protected ActionResult ViewOrJson(string viewName, object model)
{
    var useJson = false;
    //check if its an API call
    if (Request.Headers["Something"] != null)
    {
        useJson = true;
    }
    if (Request.IsAjaxRequest())
    {
        useJson = true;
    }

    if (useJson)
    {
        return Json(model);
    }
    else
    {
        if (string.IsNullOrEmpty(viewName))
        {
            return View(model);
        }
        else
        {
            return View(viewName, model);
        }
    }
}