Bottom Space to: UIView Constraint

Bottom Space to: UIView Constraint

Boy am I lost with this one. I have two UIViews "TopView" and
"BottomView". This is used to have a slide out menu when activated. I have
a simply UILabel at the bottom of the page which has a copyright message.
The Issue: When viewing the copyright message on different screen sizes it
fails. i.e.
Screen size 4" = Pass
Screen size 3.5" = Fail (as in you can't see the copyright message)
I have successfully worked out what is causing the issue which is in Xcode
adding a constraint to the bottom of UIView sets it to Superview which
works perfectly for the 4" but not the 3.5" screen size i.e.
"Bottom To Space : SuperView"
What I need to work out is how to change the constraint on the "TopView"
to be;
"Bottom To Space : Bottom Layout Guide"
Can this be done, if so how? I have a feeling it's breaking the Apple
design principles thus it can't be done. I can't believe that is the case
as I'm sure I have seen others do it.
Sorry no code as it's all in Xcode Storyboard.
Jeremy