US patent filings detail water-resistant components
The United States Patent and Trademark Office recently published a series of water-resistance patents from Apple, and the filings are shown as active. According to the patent descriptions, Apple has developed a water-resistant interface system. The patents also describe water-resistant buttons that were previously used on the Apple Watch.
Possible connection to iPhone
The patents also include descriptions of water-resistant speakers, which could most directly connect these filings to Apple's iPhone.

Apple patents published