WordPress limit access to posts/pages by user roles

wordpress-limit-access-to-post-by-user-roles

you can use such conditions to show private posts only to logged in users with role contributor. Now you only need to make post private to make that post available for contributor.
Ref: http://wordpress.stackexchange.com/questions/60582/limit-access-to-posts-pages-by-user-roles

<?php 
    if ( have_posts() ) : while ( have_posts() ) : the_post();
        $private = get_post_custom_values("private");
        if (isset($private[0]) && $private == "true") {

            if ( current_user_can( 'contributor' ) ) { //passing role to it may sometime not work
            the_title();
            the_content();
            } else {            // text to show instead the post
                echo 'this post is private, only contributor can view it';
            }

        } else {        // this is visible to all
            the_title();
            the_content();
        }

    endwhile; 
    endif; 
?>