updated April 2013
As Roger Nolan and rcw3 suggested, you can go a lot further with Uncrustify. The latest release version can be download here.
Integration Into Xcode
Integration into Xcode is dependent upon the version of Xcode that is installed.
Benoît Bourdon's BBUncrustifyPlugin-Xcode
This plugin provides access to Uncrustify right from Xcode's "Edit" menu ("Uncrustify Selected Files", "Uncrustify Active File", and "Uncrustify Selected Lines"). Just build the project and the plugin is compiled and installed.
As of April 2, 2013, Uncrustify 0.60 and an Uncrustify configuration file are include with the plugin. To use a custom Uncrustify configuration file, make sure to read the section titled "How to customize the Uncrustify configuration?" of README.md.
Note: To use Uncrustify from the command line, for example as part of a git hook, I recommend building and installing Uncrustify independently. For consistency sake, I also recommend replacing the version of Uncrustify that comes with the plugin with a link to the version Uncrustify that was independently built and installed. The following is how to do that:
cd ~/Library/Application\ Support/Developer/Shared/Xcode/Plug-ins/UncrustifyPlugin.xcplugin/Contents/Resources
mv uncrustify uncrustify.orig
ln -s /usr/local/bin/uncrustify uncrustify
Jonah Williams' Code Formatting in Xcode 4
Jonah Williams' Code Formatting in Xcode
Example Uncrustify Configuration File
The Uncrustify 0.60 configuration file that I use for Objective-C is located here.
Update the Uncrustify Configuration File for a New Version of Uncrustify
To update the Uncrustify configuration file for a new version of Uncrustify, start a Terminal and type:
mv uncrustify.cfg uncrustify.cfg.old
uncrustify -c uncrustify.cfg.old --update-config > uncrustify.cfg
To see the changes made to the Uncrustify configuration, in the terminal type:
diff uncrustify.cfg.old uncrustify.cfg
To View a Documented Version of the Uncrustify Configuration File
To view a documented version of the Uncrustify configuration file, start a Terminal and type:
uncrustify -c uncrustify.cfg --show-config