I am able to get the name and address and more from a contact with the Contacts API v3. However I just cant seem to figure out how to get the birthday. I have found this link though, but I don't really understand it since its quite different from the others.
$return[] = array (
'firstname'=> $contact['gd$name']['gd$givenName']['$t'],
'lastname'=> $contact['gd$name']['gd$familyName']['$t'],
'email' => $contact['gd$email'][0]['address'],
'phoneNumber' => $contact['gd$phoneNumber'][0]['$t'],
'city' => $contact['gd$structuredPostalAddress'][0]['gd$city']['$t'],
'street' => $contact['gd$structuredPostalAddress'][0]['gd$street']['$t'],
'country' => $contact['gd$structuredPostalAddress'][0]['gd$country']['$t'],
//I need to know what tu put here
'birthday' => $contact['gcontact$birthday'],
);
Add this in your code to get the birthday from the contacts API
'birthday' => $contact['gContact$birthday']['when'],