Have fixed this problem by added a new class “current-site” on the menu.
<?php
$blogs = get_sites();
$current_site = get_current_blog_id();
foreach( $blogs as $b ){
//$b->blog_id)
switch_to_blog($b->blog_id);
if($current_site == $b->blog_id){
wp_nav_menu(array(
'theme_location'=>'primary_menu',
'menu_class'=>'navbar current-site',
'container' => false,
'link_before' => '<span class="menu-wrap">',
'link_after'=>'</span>',
'fallback_cb' => false,
'walker' => new Walker_Nav_Pointers(),
));
} else {
wp_nav_menu(array(
'theme_location'=>'primary_menu',
'menu_class'=>'navbar',
'container' => false,
'link_before' => '<span class="menu-wrap">',
'link_after'=>'</span>',
'fallback_cb' => false,
'walker' => new Walker_Nav_Pointers(),
));
}
restore_current_blog();
}
?>