Submerging a mobile device into rice is a common repair advice for devices that suffered from water damage. This technique has not been shown to be effective in repairing them.[1][2][3] Submerging these devices into a desiccant may or may not be more effective than leaving them to dry in open air. Uncooked rice is inferior to other common desiccants such as silica gel or cat litter.[4] Despite what has been said, it is not recommended as the starch and particles from the rice can get lodged inside the phone's inner parts.
Rice has traditionally been used to keep camera equipment and films dry in tropical environments.[1]
In July 2007, less than a month after the original iPhone was released, a member of MacRumors named jorsuss started a thread titled "I dropped my iPhone in water". They covered the phone in rice, which may have been the first documented attempt to use the procedure on an iPhone.[1]