how to see the rusults of my scanned qr code

You do not need to take a photo of a QR Code, and the iPhone cannot provide a result from a photo. You just need to point the camera at the QR code, and once it is recognized it will provide you with a yellow box around the code and you should see a link at the bottom of the code. You tap on that code to get the results of the code, which most of the time is a weblink to take you to a particular website.

Thanks.

There are apps to scan QR-codes from the screen of the device they are installed in.

Just wondering which app is better for the iPhone.

All the best.

There is a picture with QR-code on the screen, which has to be scanned.

Please, explain a way to scan QR-code on the screen of the iPhone.

You would probably have to use another phone to do it. That, or print out the code and then scan it with your iPhone.