安装
https://swift.org/download/#using-downloads
1.Install required dependencies:下载安装包clang
sudo apt-get install clang libicu-dev
2.Download the latest binary release above，The swift-<VERSION>-<PLATFORM>.tar.gz file is the toolchain itself. The .sig file is the digital signature.：下载对应的swift包
我的是：swift-DEVELOPMENT-SNAPSHOT-2018-01-30-a-ubuntu16.04.tar.gz
3.If you are downloading Swift packages for the first time, import the PGP keys into your keyring:向Ubuntu系统的keyring导入新的PGP秘钥
wget -q -O - https://swift.org/keys/all-keys.asc |
gpg --import -
4.Verify the PGP signature.：更新签名验证
gpg --keyserver hkp://pool.sks-keyservers.net --refresh-keys Swift
gpg --verify swift-<VERSION>-<PLATFORM>.tar.gz.sig
gpg --verify swift-DEVELOPMENT-SNAPSHOT-2018-01-30-a-ubuntu16.04.tar.gz.sig
上面那一句，我多次都不成功，希望其他高人说明一下
5.Extract the archive with the following command:解压文件
tar xzf swift-DEVELOPMENT-SNAPSHOT-2018-01-30-a-ubuntu16.04.tar.gz
6.Add the Swift toolchain to your path as follows:添加环境变量
我的包是放在/home/test/swift-DEVELOPMENT-SNAPSHOT-2018-01-30-a-ubuntu16.04上，所以路径如下
export PATH=/home/test/swift-DEVELOPMENT-SNAPSHOT-2018-01-30-a-ubuntu16.04/usr/bin:"${PATH}"