When saving the storyboard and committing the changes to git, the chances are good that the whole
section will be removed from or added to source co
In my experience the removal only happens if you open the storyboard and have class existence related errors. An example of this is opening the storyboard while a merge conflict is not yet resolved. One or more classes might not be parse-able. In this case Interface builder seems to be removing the entire section and not only the offending class.
For me it is easily fixed by opening the storyboard again after the patch is ready in case i see the removal. If all problems are resolved, the section is regenerated. If it isn't, it means I have a problem with project settings and i shouldn't be committing anyways.