Did you actually look at how it’s implemented in the linked GitHub thread?

How it works is it takes the child view, and stuffs it into the password field. iOS automatically hides the password content (the dots) in screenshots, so by stuffing the view into there it gets hidden in screenshots. I then added the logo, and absolutely positioned the follow button on top of it. when the button is hidden, the watermark is revealed!

Absolute positioning layering hacks based on a quirk of how iOS currently handles child nodes of password fields when the dots would push content out of the parent node in screenshots. The filename of this feature is literally called “growth-hack”. I dunno what else to tell you man, but if you like it, I’m happy for you. But it’s clearly bad code.

As for the second part of your comment; normal users don’t look at source code. That argument means nothing in this context.