Cocoapods是管理iOS第三方庫的一個重要工具，下面我們就來了解一下它是如何安裝的。
由於Cocoapods的安裝時需要ruby環境的，所以一開始我們就要檢查ruby的版本：
1>打開終端，輸入ruby -v
mac@MacdeMacBook-Pro ~ % ruby -v
一般Mac OS會自帶ruby環境
ruby 2.6.3p62 (2019-04-16 revision 67580) [universal.x86_64-darwin19]
我們知道java的運行需要JVM，ruby的版本以及升級管理工具稱之爲rvm。
2>查看rvm版本，rvm -v
mac@MacdeMacBook-Pro ~ % rvm -v
可能會顯示
zsh: command not found: rvm
這個提示很明顯，說明不存在rvm。
3>安裝rvm
curl -L https://get.rvm.io | bash -s stable
4>安裝成功提示
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 194 100 194 0 0 129 0 0:00:01 0:00:01 --:--:-- 129
100 24535 100 24535 0 0 4732 0 0:00:05 0:00:05 --:--:-- 8353
Downloading https://github.com/rvm/rvm/archive/1.29.9.tar.gz
Downloading https://github.com/rvm/rvm/releases/download/1.29.9/1.29.9.tar.gz.asc
Found PGP signature at: 'https://github.com/rvm/rvm/releases/download/1.29.9/1.29.9.tar.gz.asc',
but no GPG software exists to validate it, skipping.
Installing RVM to /Users/mac/.rvm/
Adding rvm PATH line to /Users/mac/.profile /Users/mac/.mkshrc /Users/mac/.bashrc /Users/mac/.zshrc.
Adding rvm loading line to /Users/mac/.profile /Users/mac/.bash_profile /Users/mac/.zlogin.
Installation of RVM in /Users/mac/.rvm/ is almost complete:
* To start using RVM you need to run `source /Users/mac/.rvm/scripts/rvm`
in all your open shell windows, in rare cases you need to reopen all shell windows.
Thanks for installing RVM 🙏
Please consider donating to our open collective to help us maintain RVM.
👉 Donate: https://opencollective.com/rvm/donate
5>載入rvm環境
source ~/.rvm/scripts/rvm
6>查看rvm信息，輸入rvm -v
mac@MacdeMacBook-Pro ~ % rvm -v
rvm相關信息：
rvm 1.29.9 (latest) by Michal Papis, Piotr Kuczynski, Wayne E. Seguin [https://rvm.io]
7>檢查ruby可用版本，rvm list known
mac@MacdeMacBook-Pro ~ % rvm list known
顯示如下：
[ruby-]1.8.6[-p420]
[ruby-]1.8.7[-head] # security released on head
[ruby-]1.9.1[-p431]
[ruby-]1.9.2[-p330]
[ruby-]1.9.3[-p551]
[ruby-]2.0.0[-p648]
[ruby-]2.1[.10]
[ruby-]2.2[.10]
[ruby-]2.3[.8]
[ruby-]2.4[.6]
[ruby-]2.5[.5]
[ruby-]2.6[.3]
[ruby-]2.7[.0-preview1]
ruby-head
8>rvm安裝ruby環境
當ruby版本低於2.2.2時，安裝cocoapods會報錯
9>檢查ruby源，gem sources -l 結果如下：
*** CURRENT SOURCES ***
https://rubygems.org/
更換ruby源，gem source -a https://gems.ruby-china.com/
結果：https://gems.ruby-china.com/ added to sources
10>Cocoapods安裝
輸入：sudo gem install -n /usr/local/bin cocoa pods
如果有 gems installed標誌着安裝成功了。