- date: documentation ( source)
<?php
$timestamp = 1406851200;
$date = date('Y-m-d', $timestamp);
$dateTime = new \DateTime($date, new \DateTimeZone('America/Los_Angeles'));
echo $dateTime->format('Y-m-d\TH:i:sP');
echo "\n";
$dateTimeTwo = new \DateTime($date);
$dateTimeTwo->setTimezone(new \DateTimeZone('America/Los_Angeles'));
echo $dateTimeTwo->format('Y-m-d\TH:i:sP');
echo "\n";
$dateTimeThree = new \DateTime("@{$timestamp}", new \DateTimeZone('America/Los_Angeles'));
echo $dateTimeThree->format('Y-m-d\TH:i:sP');
echo "\n";
$dateTimeFour = new \DateTime("@{$timestamp}");
$dateTimeFour->setTimezone(new \DateTimeZone('America/Los_Angeles'));
echo $dateTimeFour->format('Y-m-d\TH:i:sP');
echo "\n";