Sort posts according to date

by

Here’s how I’d attack your problem (in fact I think I’ve written code like this in the past, but I can’t find it at the moment):

$blogs = array( 4, 1 );
$all_posts = array();
foreach( $blogs as $blog ) {
    switch_to_blog( $blog );
    $args = array( 'posts_per_page' => 10, 'orderby' => 'date', 'order' => 'DESC');
    $blog_posts = get_posts( $args );
    foreach( $blog_posts as $blog_post ) {
        // Add the correct permalink to the Post object
        $blog_post->permalink = get_the_permalink( $blog_post->ID );
        $all_posts[] = $blog_post;
    }
    restore_current_blog();
}

usort( $all_posts, '__sort_by_date' );

// Now you can display all your posts

foreach( $all_posts as $post ) {
    setup_postdata( $post );
    the_title( '<a href="' . $post->permalink . '">', '</a>' );
}


function __sort_by_date( $a, $b ) {
    $a_date = strtotime( $a->post_date );
    $b_date = strtotime( $b->post_date );
    if( $a_date === $b_date ) { return 0; }
    if( $a_date > $b_date ) { return 1; }
    return -1;
}

Note: I’ve updated the code to get the correct permalink for each post while we’re in the proper site (per your comment/answer below).

References