I haven’t written PHP in a while but this should be the idea:
<?php
// Options
$clientID = ''; // Required
$channelName = 'ninja';
$muted = true;
$autoplay = true;
$width = 640;
$height = 360;
// Options end
$baseURL = 'https://api.twitch.tv/helix/';
$url = $baseURL . 'streams?user_login=' . $channelName;
$ch = curl_init($url);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, true);
curl_setopt($ch, CURLOPT_HTTPHEADER, [ 'Client-ID: ' . $clientID ]);
$json = curl_exec($ch);
curl_close($ch);
$data = json_decode($json);
if(count($data->data)) {
$iframeSrc = 'https://player.twitch.tv/?channel=' . $channelName . '&muted=' . $muted . '&autoplay=' . $autoplay;
echo '<iframe src="' . $iframeSrc . '" width="' . $width . '" height="' . $height . '" frameborder="0" scrolling="false" allowfullscreen="true"></iframe>';
}
?>