I have been using a shell script as part of my Xcode build process to increment the build number within the plist file, however it's making Xcode 4.2.1 crash frequently (with an error about the target not belonging to a project; I'm guessing the changing of the plist file is confusing Xcode in some way).
The shell script did this so that the build number is only incremented by agvtool when a file is newer than the plist file (so just building didn't increment the value):
if [ -n \"`find ProjDir -newer ProjDir/Project-Info.plist`\" ]; then agvtool -noscm next-version -all; else echo \"Version not incremented\"; fi
Is there a way to increment the build number (in the plist file, or anywhere else) that doesn't break Xcode?
FINAL EDIT: I now do this kind of stuff using a python script which I have just made public on github. It's not well documented but shouldn't be difficult to work out. As a bonus this repo also contains a useful script to automatically bundle 3rd party library into an app bundle.
If I understand your question correctly, you want to modify the Project-Info.plist file, which is a part of the standard project template of Xcode?
The reason I ask this is that Project-Info.plist normally is under version control, and modifying it means that it will be marked as, well, modified.
If that is fine with you, then the following snippet will update the build number and mark the file as modified in the process, where get_build_number is some script (i.e., a placeholder in this example) to get the (possibly incremented) build number that you want to use:
#!/bin/sh
# get_build_number is a placeholder for your script to get the latest build number
build_number = `get_build_number`
/usr/libexec/PlistBuddy -c "Set :CFBundleVersion ${build_number}" ProjDir/Project-Info.plist
PlistBuddy allows you to set any key in a plist file, not just the version number. You can create all the plist files you want, and include them in the resources if needed. They can then be read in from the bundle.
As to your need to show the version in the about pane and other places, you can also look into setting CFBundleGetInfoString and CFBundleShortVersionString.