Using Xcode with Git, from: http://shanesbrain.net/2008/7/9/using-xcode-with-git and suggestions from http://stackoverflow.com/questions/456403/can-git-be-integrated-with-xcode

.gitattributes

*.pbxproj -crlf -diff -merge

.gitignore

# xcode noise
*.mode1v3
*.pbxuser
*.perspective 
*.perspectivev3
*.pyc 
*~.nib/
build/*

# Textmate - if you build your xcode projects with it
*.tm_build_errors

# old skool
.svn

# osx noise
.DS_Store
profile

Then how do you handle branching to a topic branch, creating some new files, committing, switching back to master, adding some more different files, and then merging in the topic branch?
I get a merge conflict, but have a script that fixes it by removing the >>>>>>> and <<<<<< stuff that git inserts, since I most likely want to keep all the files anyway.
If treating that file as binary fixes those issues, more power to you, and I will gladly do so as well. Just don't understand how it could.

Sounds like you've created a project, and then added it to a .git repo after the fact. You may be better off, letting Xcode (4) do the work of merging/branching within it's interface, it will do the right things, and then you won't get the merge conflicts with those files.

You can view the documentation here: http://developer.apple.com/library/mac/#documentation/ToolsLanguages/Conceptual/Xcode4UserGuide/SCM/SCM.html#//apple_ref/doc/uid/TP40010215-CH7-SW9

Also the Developer forums is a good place to get help if you're an official iOS/Mac developer.

Yeah that's right. I'm oldschool like that :)
That's good to know though, so I will give it a shot after reading the docs. Thanks for the pointers!