Is there a way to disable all notifications on the iPhone in one step? Is there a way, when doing screen recording (for online gameplay, for example), to disable all notifications in one step, so that it won't interfere with the screen recording?

Details: It can be done by turning off all notifications for 35 apps one by one, and when done with screen recording, turn them on one by one again -- but it will be 70 steps total this way.

I want to disable any notification at all, including the one that slide down showing "no preview" content -- I want to disable those as well -- everything.
Do Not Disturb does also hide notifications and you can customize it like allow incoming calls from favorites or everyone. 

When the device is locked, it won't light up the screen when receiving a message. But by enabling 'Always' on the bottom of the Do Not Disturb setting page, it will also block the notifications when your device is unlocked. 

So they won't pop up on your screen, you can only see them by opening the notification center.