MainPage.xaml

<?xml version="1.0" encoding="utf-8" ?>
<TabbedPage xmlns="http://xamarin.com/schemas/2014/forms"
             xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
             xmlns:pages="clr-namespace:CustomBottomMenu.Pages;assembly=CustomBottomMenu"
             x:Class="CustomBottomMenu.Pages.MainPage">
  
  <pages:AboutPage Icon="ic_about" />
  <pages:ContactsPage Icon="ic_contact" />
  
</TabbedPage>