php > echo strtotime("2010-12-07T23:00:00.000Z");
1291762800
echo date('c', 1291762800);
2010-12-08T00:00:00+01:00
php > var_dump(DateTime::createFromFormat('c', "2010-12-07T23:00:00.000Z"));
bool(false)
php > var_dump(DateTime::createFromFormat(DateTime::ISO8601, "2010-12-07T23:00:00.000Z"));
bool(false)

// create ISO8601 dateTime
$date = DateTime::createFromFormat(DateTime::ISO8601, '2016-07-27T19:30:00Z');

// set to user's timezone
$date -> setTimeZone('Asia/Singapore');

echo $date -> format(DateTime::ISO8601);
// prints '2016-07-28T03:30:00+0800'

DateTime::createFromFormat('Y-m-dTH:i:sP', $date)

<?php

$dates = array(
    "2010-12-07T23:00:00.000Z",
    "2010-12-07T23:00:00",
    "2010-12-07T23:00:00Z",
    "2010-12-07T23:00:00+01:00",
    (new DateTime("now"))->format(DATE_ATOM)
);

foreach($dates as $d) {

    $res = DateTime::createFromFormat(DATE_ATOM, $d);

    echo "try $d: n";
    var_dump($res);
    echo "nn";
}

?>

<?php

function parse_iso_8601($iso_8601_string) {
    $results = array();
    $results[] = DateTime::createFromFormat("Y-m-dTH:i:s",$iso_8601_string);
    $results[] = DateTime::createFromFormat("Y-m-dTH:i:s.u",$iso_8601_string);
    $results[] = DateTime::createFromFormat("Y-m-dTH:i:s.uP",$iso_8601_string);
    $results[] = DateTime::createFromFormat("Y-m-dTH:i:sP",$iso_8601_string);
    $results[] = DateTime::createFromFormat(DATE_ATOM,$iso_8601_string);

    $success = array_values(array_filter($results));
    if(count($success) > 0) {
        return $success[0];
    }
    return false;
}

// Test
$dates = array(
    "2010-12-07T23:00:00.000Z",
    "2010-12-07T23:00:00",
    "2010-12-07T23:00:00Z",
    "2010-12-07T23:00:00+01:00",
    (new DateTime("now"))->format(DATE_ATOM)
);

foreach($dates as $d) {

    $res = parse_iso_8601($d);

    echo "try $d: n";
    var_dump($res);
    echo "nn";
}

?>

Y-m-dTH:i:s.uO

$dateStr = '2015-04-29T11:42:56.000+0400'
$ISO = 'Y-m-dTH:i:s.uO'
$date = DateTime::createFromFormat($ISO, $dateStr)

$format = 'Y-m-dTH:i:s.u+';
$value = '2017-09-21T10:11:19.026Z'; // jsDate.toUTCString();
var_dump(DateTime::createFromFormat($format, $value));