Cocos2d version 3 preview
Download: Cocos2d version 3 preview
Unzip to a folder of your voice. Open terminal and navigate to the folder where you unzipped. Type ./install.sh. After this, you can delete the zip, and the unpacked folder.
In Xcode, you should now be able to create a new Cocos2d v3.x project.
Also, check the github page for more detailed instructions on how to download and install.
Unstable 1.1 version
Download 1.1 branch: cocos2d-iphone-1.1-rc0.tar.gz
Bleeding edge version
Use this command to anonymously check out the latest project source code:
$ git clone git://github.com/cocos2d/cocos2d-iphone.git $ cd cocos2d-iphone
// For the 2.x branch you should do $ git checkout develop-v2
// For the v1.x branch $ git checkout develop