Add Taxonomy Filter For Custom Post Type

functions.php

<?php
function salas_add_taxonomy_filters() {
	global $typenow;
 
	// an array of all the taxonomyies you want to display. Use the taxonomy name or slug
	$taxonomies = array('salas');
 
	// must set this to the post type you want the filter(s) displayed on
	if( $typenow == 'evento' || $typenow == 'noticia' || $typenow == 'ementa' || $typenow == 'lembrete' || $typenow == 'aluno' || $typenow == 'paginas_privadas'){
 
		foreach ($taxonomies as $tax_slug) {
			$tax_obj = get_taxonomy($tax_slug);
			$tax_name = $tax_obj->labels->name;
			$terms = get_terms($tax_slug);
			if(count($terms) > 0) {
				echo "<select name='$tax_slug' id='$tax_slug' class='postform'>";
				echo "<option value=''>Mostrar Todas as $tax_name</option>";
				foreach ($terms as $term) { 
					echo '<option value='. $term->slug, $_GET[$tax_slug] == $term->slug ? ' selected="selected"' : '','>' . $term->name .' </option>'; 
				}
				echo "</select>";
			}
		}
	}
}
add_action( 'restrict_manage_posts', 'salas_add_taxonomy_filters' );
?>