How to adapt this wordpress loop query code to include pagination? - foreach

Question

I have sourced the below code to query my posts in Wordpress and all works as intended.
I'd like to add pagination to this now. I don't want to alter the code too much now that I know it works, can anyone advise on the best way to adapt this to include the pagination?
I would like it to show a maximum of 18 posts per page and have next and prev links to other pages if they exist. This code is being used in custom category templates, but I have also setup a static page setup under the reading settings and the display of main posts uses home.php, I'd like to use the same or similar loop code to also paginate that. Any help is appreciated. Here is the code:
<div id="Items">
<ul>
<?php
// Grid sorted alphabetically
if (is_category('categoryName'))
{
$args = array( 'posts_per_page' => -1, 'orderby'=> 'title', 'order' => 'ASC', 'category' => 41 );
$categoryNameposts = get_posts( $args );
}
foreach( $categoryNameposts as $post ) : setup_postdata($post);
?>
<li><?php get_template_part( 'content', get_post_format() ); ?></li>
<?php endforeach; ?>
</ul>
</div><!-- #ItemsEnd -->

Answer 1

You should let wordpress know how much post you want to show per page in the query_posts. Replace your $args with these two lines:
$paged = (get_query_var('paged')) ? get_query_var('paged') : 1;
$args = array( 'posts_per_page' => 18, 'paged' => $paged, 'orderby'=> 'title', 'order' => 'ASC', 'category' => 41 );
Now to show Next-Previous link:
<div class="paginationClass">
<?php next_posts_link(); ?>
<?php previous_posts_link(); ?>
</div>
Also in is_category function, use categorySlug, instead of categoryName.