can i swim with my iphone 7 ? And take some pictures?

Hello,

The iPhone 7 and iPhone 7 Plus are splash, water, and dust resistant, not waterproof. It is not reccomened to intentionally wet the iPhone.

Here's more info:

About iPhone 7 and iPhone 7 Plus splash, water, and dust resistance - Apple Support

Your phone, your money, your gamble. If any amount of water gets past the water resistant protection, you are screwed cause the warranty clearly states that damage is NOT covered.

You could consider a LifeProof shell, which altogether would result in total waterproof protection. They are amongst the thinnest and least intrusive to achieve that level of protection.

Can you swim with it? Sure you can. Will the phone still work if you take it underwater? I highly doubt it.