Install an Xcode plugin
So you just downloaded the awesome Xcode code completion plugin (or any other) and you need to get it working… easy. You can install any Xcode plugin by dropping the .pbplugin file into the following directory:
If you haven’t used plugins yet, the Plug-ins directory does not exist. In this case, all you need to do is create the directory. After you have dropped the plugin file into the folder, relaunch Xcode and the plugin will be loaded automatically. Uninstalling a plugin is just a matter of removing it from the Plug-ins folder.