I did not know this. Another way to quickly get to the top of tables in iOS, assuming you're in an app, is to double tap the button of whatever page you're in in the navigation bar at the bottom. Some apps somehow disable this but it's the default behavior built into the OS.
Tapping the button of the tab you're on doesn't always scroll to the top; it does always scroll to the default position. In the "All Photos" tab of the Photos app, which is sorted with newest photos at the bottom, tapping the tab again will bring you down to the bottom, as that's the default position.
