functions.php

<?php 
//Aşağıdaki kodlar functions.php içine eklenecek

add_action( 'generate_rewrite_rules', 'ilan_ek_kurallar_temiz' );
function ilan_ek_kurallar_temiz( $wp_rewrite ) {
    $new_rules = array( 
        'products/([^/]+)/?$' => 'index.php?sehir=' . $wp_rewrite->preg_index( 1 ),
        'products/([^/]+)/([^/]+)/?$' => 'index.php?post_type=ilan&sehir=' . $wp_rewrite->preg_index( 1 ) . '&ilan=' . $wp_rewrite->preg_index( 2 ),
        'products/([^/]+)/([^/]+)/page/(\d{1,})/?$' => 'index.php?post_type=ilan&sehir=' . $wp_rewrite->preg_index( 1 ) . '&paged=' . $wp_rewrite->preg_index( 3 ),
        'products/([^/]+)/([^/]+)/([^/]+)/?$' => 'index.php?post_type=ilan&sehir=' . $wp_rewrite->preg_index( 2 ) . '&ilan=' . $wp_rewrite->preg_index( 3 ),
        'products/([^/]+)/([^/]+)/([^/]+)/([^/]+)/?$' => 'index.php?post_type=ilan&sehir=' . $wp_rewrite->preg_index( 3 ) . '&ilan=' . $wp_rewrite->preg_index( 4 ),
    );
    $wp_rewrite->rules = $new_rules + $wp_rewrite->rules;
}
function alt_kategorileri_duzenleyen_kural($query) {
	if ( isset( $query['post_type'] ) && 'ilan' == $query['post_type'] ) {
			if ( isset( $query['ilan'] ) && $query['ilan'] && isset( $query['sehir'] ) && $query['ilan'] ) {
					$query_old = $query;
					if ( 'page' == $query['sehir'] ) {
							$query['paged'] = $query['name'];
							unset( $query['sehir'], $query['name'], $query['ilan'] );
					}
					$query['fields'] = 'ids';
					$query['posts_per_page'] = 1;
					$_query = new WP_Query( $query );
					if ( ! $_query->posts ) {
							$query = array( 'sehir' => $query['ilan'] );
							if ( isset( $query_old['sehir'] ) && 'page' == $query_old['sehir'] ) {
									$query['paged'] = $query_old['name'];
							}
					}
			}
	}
	return $query;
}
add_filter( 'request', 'alt_kategorileri_duzenleyen_kural', 10 );

function son_bir_yazilar_icin_duzenleme($link, $post)
{
    if ($post->post_type != 'ilan')
        return $link;

    if ($cats = get_the_terms($post->ID, 'sehir'))
    {
        $link = str_replace('%sehir%', get_taxonomy_parents(array_pop($cats)->term_id, 'sehir', false, '/', true), $link); // see custom function defined below\
        $link = str_replace('//', '/', $link);
        $link = str_replace('http:/', 'http://', $link);
    }
    return $link;
}
add_filter('post_type_link', 'son_bir_yazilar_icin_duzenleme', 10, 2);

function get_taxonomy_parents($id, $taxonomy, $link = false, $separator = '/', $nicename = false, $visited = array()) {    
	$chain = '';   
	$parent = get_term($id, $taxonomy);

	if (is_wp_error($parent)) {
			return $parent;
	}

	if ($nicename)    
			$name = $parent -> slug;        
else    
			$name = $parent -> name;

	if ($parent -> parent && ($parent -> parent != $parent -> term_id) && !in_array($parent -> parent, $visited)) {    
			$visited[] = $parent -> parent;    
			$chain .= get_taxonomy_parents($parent -> parent, $taxonomy, $link, $separator, $nicename, $visited);

	}

	if ($link) {
			// nothing, can't get this working :(
	} else    
			$chain .= $name . $separator;    
	return $chain;    
}

post-type.php

<?php 
//Aşağıdaki eklemeler post type ve taxonomy tanımına eklenmeli

//Post Type için
'rewrite' => array( 'slug' => 'ilan/%sehir%', 'hierarchical' => true, 'with_front' => false )

//Taxonomy için

'rewrite' => array( 'slug' => 'sehir', 'hierarchical' => true, 'with_front' => false ),

taxonomy-sehir.php

<?php
$sehiri = get_queried_object();
if($sehiri->parent != 0 ) {
	$ilce_selected = $sehiri->slug;
	$slug_getir = get_term_by('id',$sehiri->parent,'sehir');
	$sehir_selected = $slug_getir->slug;
	$yazi = $sehiri->name ." İlanlar";
	$child = $sehiri->parent;
} else {
	$ilce_selected = '';
	$sehir_selected = $sehiri->slug;
	$yazi = $sehiri->name ." İlanlar";
	$child = $sehiri->term_id;
}
?>
<form action="<?php esc_url(bloginfo('url')); ?>/" method="get">
	<?php
	$args = array(
		'taxonomy' => 'sehir',
		'name' => 'sehir',
		'show_option_all' => 'Şehir Seçiniz',
		'hierarchical' => 1,
		'depth' => 1,
		'show_count' => 0,
		'orderby' => 'name',
		'order' => 'ASC',
		'echo' => 0,
		'value_field' => 'slug',
		'hide_empty' => 1,
		'selected' => $sehir_selected
	);
	$select = wp_dropdown_categories($args);
	$select = preg_replace("#<select([^>]*)>#", "<select$1 onchange='return this.form.submit()'>", $select);
	echo $select;
	?>
	<noscript><input class="rtd-btn primary" type="submit" value="View" /></noscript>
</form>
<form action="<?php esc_url(bloginfo('url')); ?>/" method="get">
	<?php
	$args2 = array(
		'taxonomy' => 'sehir',
		'name' => 'sehir',
		'show_option_all' => 'İlçe Seçiniz',
		'hierarchical' => 1,
		'depth' => 1,
		'show_count' => 0,
		'orderby' => 'name',
		'order' => 'ASC',
		'echo' => 0,
		'value_field' => 'slug',
		'hide_empty' => 1,
		'selected' => $ilce_selected,
		'child_of' => $child
	);
	$select2 = wp_dropdown_categories($args2);
	$select2 = preg_replace("#<select([^>]*)>#", "<select$1 onchange='return this.form.submit()'>", $select2);
	echo $select2;
	?>
	<noscript><input class="rtd-btn primary" type="submit" value="View" /></noscript>
</form>
<h1><?php echo $yazi; ?></h1>