I've talked about package managers for OS X as well as for package managers for code. There is also a very useful, but probably lesser known package manager for Xcode, called Alcatraz.io. In its own words:
Alcatraz is an open-source package manager for Xcode. It lets you discover and install plugins, templates and color schemes without the need for manually cloning or copying files. It installs itself as a part of Xcode and it feels like home.