Alternate post types in Wordpress template

Question

I currently have this code in my page template that displays 3 'Portfolio' Items and then 3 'News' Items...

<?php
        $portfolio_args = array(
            'post_type' => 'portfolio',
            'posts_per_page' => 3
        );

        $portfolio = new WP_Query($portfolio_args);

        while($portfolio->have_posts()) {
            $portfolio->the_post();
            $post = new SeedPost(get_the_ID());
            $post->display();
        }
        wp_reset_query();

        $news_args = array(
            'post_type' => 'post',
            'posts_per_page' => 3
        );

        $news = new WP_Query($news_args);

        if($news->have_posts()) {
            while($news->have_posts()) {
                $news->the_post();
                $post = new SeedPost(get_the_ID());
                $post->display();
            }
        }
        wp_reset_query();
        ?>

Would it be possible to alternates how these display? so instead of displaying like this:

Portfolio    Portfolio    Portfolio 

News         News         News

It displays like this:

Portfolio     News         Portfolio

News          Portfolio    News

UPDATE>>>>>>>

I have tried to implement a solution from another post here:

$portfolio = array(
            'post_type' => 'portfolio'
        );

        $news = array(
            'post_type' => 'post'
        );

        $new = array();
        for ($i=0; $i<count($portfolio); $i++) {
           $new[] = $portfolio[$i];
           $new[] = $news[$i];
        }
        var_dump($new);

But it doesn't seem to be working and I don't really understand PHP well enough to know whats wrong...

Many thanks

Answer 1

OK so, without knowing whether $post->display() function relies on the global post object/query its worth trying this:

<?php
    global $post;

    $portfolio_args = array(
        'post_type' => 'portfolio',
        'posts_per_page' => 3
    );

    $portfolio_posts = get_posts($portfolio_args);

    foreach ($portfolio_posts as $portfolio_post) {
        $posts_list['portfolio'][] = $post;
    }

    $news_args = array(
        'post_type' => 'post',
        'posts_per_page' => 3
    );

    $news_posts = get_posts($news_args);

    foreach ($news_posts as $news_post) {
        $posts_list['news'][] = $post;
    }

    for ($i = 0; $i < count($posts_list['portfolio']); $i++) {
        $post = $posts_list['portfolio'][$i];
        setup_postdata($post);
        $post = new SeedPost(get_the_ID());
        $post->display();
        wp_reset_postdata();

        if (isset($posts_list['news'][$i])) {
            $post = $posts_list['news'][$i];
            setup_postdata($post);
            $post = new SeedPost(get_the_ID());
            $post->display();
            wp_reset_postdata();

            unset($posts_list['news'][$i]);
      }
    }

    /* If there are any left news. */
    foreach($posts_list['news'] as  $post) {
       setup_postdata($post);
       $post = new SeedPost(get_the_ID());
       $post->display();
       wp_reset_postdata();
    }
?>

Answer 2

You're missing just the actual "getting the posts". In a case like this, get_posts is indicated instead of WP_Query as it returns a simple array that we have to iterate to extract the information.

$portfolio_args = array(
     'post_type' => 'portfolio',
     'posts_per_page' => 3
 );
 $portfolio = get_posts($portfolio_args);

 $news_args = array(
     'post_type' => 'post',
     'posts_per_page' => 3
 );
 $news = get_posts($news_args);

 $all = array();
 for ($i=0; $i<count($portfolio); $i++) {
    $all[] = $portfolio[$i];
    $all[] = $news[$i];
 }

# Debugging, uncomment to check the variable
// printf('<pre>%s</pre>', print_r($all,true));

 for ($i=0; $i<count($all); $i++) {
    // to get the post title use $all[$i]->post_title and so on
    $post = new SeedPost($all[$i]->ID);
    $post->display();
 }

Printed:

Array
(
    [0] => WP_Post Object
        (
            [ID] => 25
            [post_author] => 1
            [post_date] => 2017-05-11 13:38:57
            [post_content] => 
            [post_title] => a portfolio item
            ...
            [post_type] => portfolio
            ...
        )

    [1] => WP_Post Object
        (
            [ID] => 17
            [post_author] => 1
            [post_date] => 2017-05-07 12:32:52
            [post_content] => 
            [post_title] => a post
            ...
            [post_type] => post
            ...
        )

    [2] => WP_Post Object
        (
            [ID] => 24
            [post_author] => 1
            [post_date] => 2017-05-11 13:38:40
            [post_content] => 
            [post_title] => 
            ...
            [post_type] => portfolio
        )

    [3] => WP_Post Object
        (
            [ID] => 15
            ...
            [post_type] => post
            ...
        )

    [4] => WP_Post Object
        (
            [ID] => 23
            ...
            [post_type] => portfolio
            ...
        )

    [5] => WP_Post Object
        (
            [ID] => 13
            ...
            [post_type] => post
            ...
        )

)