iPhone dropped in saltwater, still turns on

You first off need to disconnect the battery immediately. It started corroding the second it hot wet.when power is connected it corrodes faster. You can try a sonic bath with Branson ec cleaner and rinse it an alcohol bath and dry it but there is not guarantee that will keep it alive long enough to get your data off of it. Pretty much all repair shops won't touch a phone with water damage except to retrieve data. Once they are wet they will never work right again. If that doesn't work you can send in for data recovery. I would recommend jessa at ipad rehab ipadrehab.com she charges a flat fee which I believe is 300 dollars and if she can't retrieve the data there is no charge.