Question posted in 
I am having trouble pinning the UIButton to the bottom of my UIViewController, (There is a tab bar if that helps).
Here are the constraints of the UIButton.
Originally, it all worked fine, but ever since I added iPad support to the application I have issues. on the iPad the UIButton is pinned to the bottom of the screen, directly above the tab bar. However on iPhone, there is this empty gap at the bottom.
What I Tried
Doing some research I saw that sometimes split view controller causes a grey bar, I added this line of code to resolve it and it fixed the bottom bar , but this constraint issues is still causing me a headache.
self.extendedLayoutIncludesOpaqueBars = true
iPad View Hierarchy
iPhone View Hierarchy
4
Answers
Remove current Constrain and Try unchecking "Constrain to margins" button.
You have an option on Xcode to vary your constraint depending of the size of the screen.
You can create two constraints, one that works on iPad, one that works on "classic" iPhone.
Here, if I create a new constraint during the variation, I can then select on the right window which variation you want the constraint to be installed on.
There is a whole topic about that here
1- Give it a constant height for example 40
2- While setting constraints, uncheck (Constrain to margins)
3- Give it a proportional width constraint with the super view 0.8
Note1: If you don’t want to give it a fixed height you can do the same step 3 but with height and not 0.8 but maybe 0.2 to less depending on your design.
Note2: You can use a scroll view, it will make it so easy for you
Try setting a constraint to a View instead of a SafeArea