So I've got a scenario where I've built an app for iOS and want to replace one of the built .mm files with a custom one where I've editing some of the code.

I can just edit it in Xcode, but I'd rather get the process automated so that I can do the same thing for multiple projects.

I try to use pbxProject.ReplaceFile() in an editor script with the IPostprocessBuildWithReport interface, but it doesn't seem to be doing what I wanted.