This script will download all the WWDC 2018 sample code. You can simply install WWDC-Downloader as a ruby gem like this:
gem install wwdcdownloader
or
sudo gem install wwdcdownloader
Run the script like this:
wwdcdownloader [<target-dir>]
The script will create a directory called "wwdc2018-assets" (or target-dir if given) in the directory you run the script from.
That's it. Enjoy and see you next year.