Hello,
I don't want to click the link you found since its not Apple but wanted to mention they have their own guide. Also, it's important to understand the difference between water proof and water resistant. Apple does not claim that any iPhone model is water proof.
About splash, water, and dust resistance of iPhone 7 and later - Apple Support
"These models have a rating of IP67 under IEC standard 60529 (maximum depth of 1 meter up to 30 minutes):
- iPhone SE (2nd generation)
- iPhone XR
- iPhone X
- iPhone 8
- iPhone 8 Plus
- iPhone 7
- iPhone 7 Plus
Splash, water, and dust resistance are not permanent conditions and resistance might decrease as a result of normal wear. Liquid damage is not covered under warranty, but you might have rights under consumer law."
"What should I do if my iPhone gets wet?
- If a liquid other than water splashes on your iPhone, rinse the affected area with tap water.
- Wipe your iPhone off with a soft, lint-free cloth—for example, a lens cloth.
Make sure that your iPhone is dry before opening the SIM tray.
To dry your iPhone, tap it gently against your hand with the Lightning connector facing down to remove excess liquid. Leave your iPhone in a dry area with some airflow. Placing your iPhone in front of a fan blowing cool air directly into the Lightning connector might help the drying process.
Don't dry your iPhone using an external heat source or insert a foreign object, such as a cotton swab or a paper towel, into the Lightning connector.
Your iPhone can warn you if there's liquid in the Lightning port when you connect a Lightning cable or an accessory to your iPhone XS, iPhone XS Max, iPhone XR, or later. Learn what to do if you see a liquid-detection alert on your iPhone."
I hope this helps.
