How to sort images by date modified?

Question

This code is sorting the images alphabetically. How to do sorting by date? So users will be more convenient to view the new image.

Here is the code:

<link href="assets/css/gallery.css" rel="stylesheet">
<link href="assets/css/dope.css" rel="stylesheet">
<div class="row center">
    <ul class="uk-tab" id="gamemodelistregion" uk-switcher="connect: + ul; animation: uk-animation-fade">
    <li aria-expanded="true" class="uk-active">
        <a>All skins</a>
        <?php
            # Skin directory relative to include/gallery.php (this file)
            $skindir = "../skins/";

            # Skin directory relative to index.html
            $skindirhtml = "./skins/";

            $images = scandir($skindir);

            foreach($images as $curimg) {
                if (strtolower(pathinfo($curimg, PATHINFO_EXTENSION)) == "png") {
        ?>
        <li class="skin" onclick="$('#nick').val('{' + $(this).find('.title').text() + '} ');" data-dismiss="modal">
            <div class="circular" style='background-image: url("./<?php echo $skindirhtml.$curimg ?>")'></div>
            <h4 class="title"><?php echo pathinfo($curimg, PATHINFO_FILENAME); ?></h4>
        </li>
        <?php
                }
            }
        ?>
    </li>
</ul>
</div>

Answer 1

The filemtime function returns a Unix timestamp of the file's last modification date.

// retrieve all images but don't waste time putting them in alphabetical order
$images = scandir($skindir, SCANDIR_SORT_NONE);

// remove all non-existent files and non-PNG files
$images = array_filter($images,
  function($file) use ($skindir) {
    $path = "$skindir/$file";
    return file_exists($path) && strtolower(pathinfo($path, PATHINFO_EXTENSION)) == "png";
  }
);

// sort image by modification time in descending order
usort($images, function($a,$b){return filemtime($a)-filemtime($b);});

// now you can iterate through images and print them
foreach($images as $curimg): ?>
  <!-- Output image HTML here -->
<?php
endforeach;