Records of birth, marriage and death are kept in the local civil registrars office in the local gmina if they are under 100 years old.
Using http://mapa.szukacz.plhttp://mapa.szukacz.pl I found several places name Swiniary or it was part of their name.The closest one to the city of Krakow is this one:
7. wieœ Œwiniary 391 osób woj. ma³opolskie pow. bocheñski gmina Drwinia kod: 32-709 prefiks tel.: 012
The gmina is Drwinia.This is their homepage:http://www.drwinia.gmina.pl/statutg.phphttp://www.drwinia.gmina.pl/statutg.php.Their physical address (adres) is in section 3 in the middle of the page.You should have your father request his father's birth record, since he is the closest next of kin.He should submit a copy of his father's death certificate and a copy of his birth own birth certificate.The letter should be written in Polish and a request on how much the record will cost should be included.
Search around maybe you can find an email address for them.Many of them now have email addresses.