Wet iphone4 -Help

Hi everyone,

This morning, I accidentally dropped my iphone into the toilet ( I know, it sounded stupid). At that time it was working, however, it automatically turn off right away, I try to shake off any water left, and then use a hair dryer to dry out, especially at where the charger adapter is. Then, suddenly, it got hot, really hot, then after few hour it cool down. I put it under the sunshine for the water to evaporate. Then I went online and read the article, most of you saying that we should put it into a raw rice bag. I wonder this tip still work with my iphone now. Because my friend said to me that the phone get hot, it means there is something wrong inside with the hardware already, so the only way I could do right now is take it to the Apple store and ask for the help. Does any one have any suggestion for my case? My phone is still under the warranty, and i also bought an additional Apple care, but I guess it is no useful in this case.

With my case, does anyone know how much it will cost to get the phone to be repaired?

thank you very much for any help, I appreciate it!