I noticed that, since I updated Unity yesterday, when I build my project to iOS it no longer allows me to append my build to a previous one. The only option is “replace” and I’m worried I will lose the changes I have made in xcode when I replace the existing project.
Every time you update a Unity version you have to re-build your iOS projects from scratch. If you don’t need any 3.4.1 features, keep working in 3.4 so you can keep appending to your existing Xcode project until release (If it’s really too much work to make your changes in Xcode again). If you really need 3.4.1, you will need to build a new iOS Xcode project and make your changes again.
This has always been the case with new Unity versions, as things change under the hood and Xcode projects are not always compatible, so rather than having a busted and un-fixable project, you are forced to re-make your Xcode project.