Upgrading Old Interface Builder Files
This morning I was working on my Potentials app for macOS, and I realized that the Auto Layout constraints were not being set properly, and the Xcode 10.2.1 UI wasn't showing the existing constraints, either. I noticed this was still a nib file, and I know Xcode has moved to xib files many years ago, so I looked up how to upgrade the file's contents.
The solution was pretty easy:
$ cd Base.lproj/ $ ibtool MainMenu.nib --upgrade --write MainMenu.xib
and then I can add the MainMenu.xib to the project, and delete the MainMenu.nib from the project. Check it all in, and we're done.
My concern is that Xcode should have said something. Like "Upgrade this file", or "Let me upgrade this file"... but leaving it alone and not really working right - that's not really a good thing to do. Still... I've been using these tools long enough, I had a feeling it was something like this.