WordPress: get category link by custom field.

category-custom_field-link.php

<?php
/**
 * Get category link by custom field.
 * Uses custom field that matches category slug.
 */
function mytheme_category_link() {
	global $post;

	$cat_slug = get_post_meta( $post->ID, 'catslug', true);
	$catid = get_category_by_slug( $cat_slug );
	$id = $catid->term_id;

	$category_link = get_category_link( $id );

	echo '<a class="view-more" href="' . $category_link . '">' . __( 'View More', 'mytheme' ) . '</a>';
}