How long does it take to built abs by swimming freestyle?

Hi, i personally love swimming and favourite swimming stroke is freestyle. I went to swimming 6 to 7 days per week and it uses only purely freestyle. I swan 30 to 40 laps of 50 meters per day. But I am just curious does swimming burn fats and does swimming built 6-packs? As I have been article stating that by swimming freestyle you are able to burn fats as well as to built 6-packs. But does anyone here successfully burn fats and built 6-packs by purely doing swimming? If yes, how long will it take for people like me to burn fats and built 6-packs? I do need your guidance.