PHP delete cookie not working on safari when open 2 taps -

PHP delete cookie not working on safari when open 2 taps -

i delete cookie command

unset($_cookie['login']); setcookie('login', null, -1, '/');

it works when open 1 tap on safari. if open 2 taps not working. cookie not empty. when unserialize($_cookie['login']) error:

notice: unserialize(): error @ offset 0 of 7 bytes

it's ok on chrome , firefox.

php cookies safari