32gb xperia s for iphone 4 -

hi i have a xperia s in good condition its 4 months old with the usual wear and tear nothing bad tho as the mobile id good its sim free and has 32bg memory. i have the box and all the bits that cam with plus 4 nfc tags. i would like to swap it for a iphone 4 it has to be unlocked and atleast 16gb thanks 07565517630 plus the xperia s is still under warranty