Git and pbxproj

Question

I was looking at an open source Mac application, and they gave some suggested values for .gitignore. They were what I would expect...

However, they also suggested an entry into a .gitattributes file:

*.pbxproj -crlf -diff -merge

I'm not the most knowledgable in terms of git, so I was wondering - what exactly are the benefits of adding this line? What does do in particular? I've only seen this suggested in this one project, and if it was normal practice I would have expected to see it elsewhere right now. So I was curious about how it applies to the pbxproj file specifically.

Answer 1

I faced the problem of corruption *.pbxproj file after resolving merge conflicts manually. Or, more often, my files just 'disappeared' from the working tree after the merge. It drove me mad because we work in a team, so you can imagine how messy it can become very fast.

So, I have tested merge=union and it works well so far. I know that it can't help if files were deleted or renamed at the same time, but for adding new files it works as expected: there is no conflicts and files don't disappear after the merge. And it also saves quite a bit of time.

If you want to try it out, here is what I did.

1) Create a global .gitattributes file. Run in terminal:

touch ~/.gitattributes
git config --global core.attributesfile ~/.gitattributes

2) This command should open it in a text editor:

open ~/.gitattributes

3) When the file opens, add this line and save the file:

*.pbxproj binary merge=union

Done. Hope this will help new readers like it helped me.

Answer 2

I wrote a python script named xUnique to solve this merge conflicts problem.

This script do following things:

• replace all 24 chars UUID to project-wide unique 32 chars MD5 digests, and remove any unused UUIDs(usually caused by careless merge before). This would prevent duplicate UUIDs because different machines/Xcode generate different UUIDs in this file. Xcode does recognize it and the project could be opened. During this process, remove all invalid lines in project file
• sort the project file. I wrote a python version of sort-Xcode-project-file from Webkit team with more new features:
  • support to sort PBXFileReference and PBXBuildFile sections
  • remove duplicated files/refs
  • avoid creating new file even if no changes made, this makes less commits after using this script

More details and updates of xUnique, please refer to README

Answer 3

A diff is oftentimes useful at commit time to check what has been changed. So I find it useful to keep the diffing ability but just prevent merging. So I use this in my .gitattributes file:

*.pbxproj -crlf -merge

On another note, has anybody tried using merge=union for pbxproj files? See: Should I merge .pbxproj files with git using merge=union?

Answer 4

The pbxproj file isn't really human mergable. While it is plain ASCII text, it's a form of JSON. Essentially you want to treat it as a binary file.

Here's what the individual flags do:

-crlf: don't use crlf <=> cr conversion

-diff: do not diff the file

-merge: do not attempt to merge the file

From the Pro Git book by Scott Chacon

Some files look like text files but for all intents and purposes are to be treated as binary data. For instance, Xcode projects on the Mac contain a file that ends in .pbxproj, which is basically a JSON (plain text javascript data format) dataset written out to disk by the IDE that records your build settings and so on. Although it’s technically a text file, because it’s all ASCII, you don’t want to treat it as such because it’s really a lightweight database — you can’t merge the contents if two people changed it, and diffs generally aren’t helpful. The file is meant to be consumed by a machine. In essence, you want to treat it like a binary file.