Installing Swift on Ubuntu
Downloads for recent Ubuntus (14.04 LTS and 15.10 at the time of writing) are available from the Swift homepage as compressed tar archives.
Installation goes as follows (untested):
# download, then...
tar xfz swift-2.2-RELEASE-ubuntu14.04.tar.gz ~
ln -s ~/swift-2.2-RELEASE-ubuntu14.04/usr/ ~
export PATH=~/usr/bin:"$PATH" # better in .bashrc