How to center a button above a tableview with the storyboard in swift?

Question

I would like to get this result (storyboard view):

But when I simulate my app, I get this result (without any constraints)

So I tried to add some constraints to center the table view. But when I add any constrain, the TableView disappears. Why?

Answer 1

Remove all old constraint first and set constraint as shown in below images:

For Button:

For TableView:

Result:

Answer 2

As below, add two constraints is enough.

Answer 3

You should have 4 constraints for the button:
to the top
to the left (alternatively to the middle)
to the right (alternatively constant width)
constant height

And 4 to the tableview:
the top to the bottom of the button
to the left
to the right
to the bottom of the screen

Check out this tutorial if you dont understand autolayout: http://www.raywenderlich.com/115440/auto-layout-tutorial-in-ios-9-part-1-getting-started-2