This "rice trick" is for amateurs who are clueless about electronics and repairs. Yes, rice will absorb SOME of the water, but there's a battery inside your iPhone which you CANNOT remove unless you take it apart - a battery which is pumping electricity through an iPhone full of liquid... and that's called electrolysis, and it means that the internals have a VERY high chance of corroding. If the rice was GUARANTEED to absorb ALL the water from ALL the hidden nooks and crannies IMMEDIATELY, you may stand a better chance, but water inside an electronic device can become trapped, and remains in place stubbornly by surface tension, until it is completely disassembled and cleaned professionally, usually with an ultrasonic tank and alcohol solution of sorts, and then dried gently in a low temperature convection oven.
This water can remain trapped under perforated RF shielding cans
(RF circuits are VERY VERY VERY sensitive precision instruments, the operational parameters of which may be altered SIGNIFICANTLY by even the grease of a fingerprint!), lodged inside a microphone capsule, inside a vibration motor housing... the list is endless.
This "rice trick" is not a magic solution to save water damage - it is, at best, moderately effective and more a placebo.
Source: Qualified electronic repair engineer since 1991.
Electrolysis:
https://www.youtube.com/watch?v=bdgPQZ4CIBQ
"iFixit" advice on removing the battery immediately: https://www.ifixit.com/Answers/View/70976/What+should+I+do+if+my+iPhone4s+got+water+damaged
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TERRIBLE advice, and most definitely NOT what you ought to do; read my post.