To setup external submodules such as RestKit, run the installation script in this directory:
./install.sh
This also performs a build of all libraries required by the sample apps, as well as the sample apps themselves. In addition it installs the Force.com app templates into the default XCode projects template location under ~/Library/Developer/Xcode/Templates. (This allows to you create new projects of either type Native Force.com-based App or Hybrid Force.com-based App directly from Xcode.)
After you git clone, you need to add the upstream repo (pointing to the public repo):
git remote add upstream git@github.com:forcedotcom/SalesforceMobileSDK-iOS.git
To pull changes from our public repo:
git fetch upstream
git merge upstream/master