I'm using Xcode 5 and autolayout in my project. I have a .xib file with a lot of subviews and constraints between them. Now I need to create an intermediate fullscreen container view and put all subviews there. So now I have view->subviews, and I want view->container view->subviews. When I do this in IB by dragging subviews into container view, they all get centred and all constraints get lost. It's going to be a little hard to restore all constraints manually. Is there a smart way to do this keeping all subviews' positions and constraints?
Add your container view to the hierarchy (to get an object ID) in Interface Builder and close the view. Edit the .xib file manually, in a text editor, and move all subviews to be under the container view. Constraints are created in IB with references to IB object IDs, so you will have to replace the constraints from referencing the superview with the container; a quick replace run should be sufficient.
You can do this in Xcode 6 by using cut&paste to a separate view (which you can later drag around to wherever you actually need it).
来源：https://stackoverflow.com/questions/22331069/move-all-subviews-to-container-view-keeping-positions-and-constraints