App suica - do I need to keep the App open?

Hello,
I have heard from a youtube video that to pass through turnstiles at train station, you do need to open the app to scan. I mean, not that hard, but when the place is crowded and you take 4 seconds to open it, can get a bit stressing. Is it true that you have just to put the phove over the the QR reader?

It's not a QR code. It's RFID (like radio). I don't know about any "app" but on iPhones if you have a Suica card in your wallet you can set it up to be used without doing anything.

Cool, thanks.