KeyboardLayoutConstraint: Space above keyboard?

[Nathipha]

First of all: Thanks for posting the code for this!

It's working well with Swift 5/Xcode 10 but there's something weird I can't explain and that I haven't been able to fix yet:

When the keyboard is opened, there's always a space of about 50pts above it that doesn't seem to be useable, which makes one of my UI elements decrease its height, even though there should be enough space for it.

I opened a Stackexchange question here, explaining it in detail.

How do I get rid of this additional space or at least decrease its height to something like 10pts?