For more details ( Size Classes and Adaptivity through Storyboard) of using auto layout for adaptivity in iOS, we can follow the apple developer site link.
We can also add constraints Programatically using Visual Format Language as described here at apple developer site.
We can add adaptivity to any subclass of
UIView which we add on view controller in nib file.
Lets take an example of adding adaptivity using size classes to a view.
These constraints defines that the added view will be placed in it's superview as
CGRect(20, 0, superview.width - 20, superview.height - 20)
We can also see the preview with landscape mode by moving mouse on the name of device and clicking the rotation button as: