如果使用全局循环来显示帖子，那么可以使用pre_get_posts 行动

function restrict_categories_for_user( $query ) {
    if ( ! is_admin() && $query->is_main_query() && get_current_user_id() ) {
        $user = wp_get_current_user();
        if ( in_array( \'viewer_a\', (array) $user->roles ) ) {
            // The user has the "viewer_a" role
            $query->set( \'category_name\', \'cat_A\' );  // <- use category slug here
        }
        if ( in_array( \'viewer_b\', (array) $user->roles ) ) {
            // The user has the "viewer_b" role
            $query->set( \'category_name\', \'cat_B\' );  // <- use category slug here
        }
    }
} 
add_action( \'pre_get_posts\', \'restrict_categories_for_user\' );