最好先安装完Xcode，并且保证安装了Xcode Command Line Tool！ 最好先安装完Xcode，并且保证安装了Xcode Command Line Tool！！ 最好先安装完Xcode，并且保证安装了Xcode Command Line Tool！！！ 重要的事情说三遍，不然可能会遇到各种问题。
CocoaPods升级1.5.3
sudo gem install -n /usr/local/bin cocoapods -v 1.5.3
最新的CocoaPods安装教程
打开终端：>_
1、查看当前Ruby版本
ruby -v
2、升级Ruby环境，首先需要安装rvm（第一步要下载一些东西等两分钟左右）
curl -L get.rvm.io | bash -s stable
source ~/.bashrc
source ~/.bash_profile
3、查看rvm版本
rvm -v
显示如下(或者是其他版本)
rvm 1.29.3 (latest) by Michal Papis, Piotr Kuczynski, Wayne E. Seguin [https://rvm.io]
4、列出ruby可安装的版本信息
rvm list known
显示如下
# MRI Rubies
[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[.7]
[ruby-]2.4[.4]
[ruby-]2.5[.1] // 重点在这里 重点在这里 重点在这里
[ruby-]2.6[.0-preview2] // 测试版
ruby-head
.....
5、安装一个ruby版本（这里我选择的是2.5.1版本，当然你也可以选择其他的）
rvm install 2.5.1
// 注意:安装过程中需要两次按下 Enter 键, 第二次按下后需要输入电脑访问密码(不可见,只管输入就行);
// 如果你电脑没有安装Xcode和Command Line Tools for Xcode以及Homebrew 会自动下载安装,建议提前安装这三者.
这里很多小伙伴会遇到错误，大部分是因为没有安装Homebrew造成，所以所以所以要提前安装比较好
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
6、设置为默认版本
rvm use 2.5.1 --default
7、更换源
sudo gem update --system
gem sources --remove https://rubygems.org/
gem sources --add https://gems.ruby-china.com/
8、为了验证你的Ruby镜像是并且仅是ruby-china，执行以下命令查看
gem sources -l
如果是以下结果说明正确，如果有其他的请自行百度解决
*** CURRENT SOURCES ***
https://gems.ruby-china.com/
9、这时候才正式开始安装CocoaPods
sudo gem install -n /usr/local/bin cocoapods
10、如果安装了多个Xcode使用下面的命令选择（一般需要选择最近的Xcode版本）
sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer
11、安装本地库
pod setup
注意：有时候这里会报一些ruby相关的错误：
Traceback (most recent call last):
6: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/bin/ruby_executable_hooks:10:in `'
5: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/executable-hooks-1.6.0/lib/executable-hooks/hooks.rb:49:in `run'
4: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/executable-hooks-1.6.0/lib/executable-hooks/hooks.rb:49:in `each'
3: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/executable-hooks-1.6.0/lib/executable-hooks/hooks.rb:50:in `block in run'
2: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/rubygems-bundler-1.4.5/lib/rubygems_executable_plugin.rb:4:in `block in '
1: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:92:in `require'
/Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:92:in `require': cannot load such file -- rubygems-bundler/noexec (LoadError)
10: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/bin/ruby_executable_hooks:10:in `'
9: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/executable-hooks-1.6.0/lib/executable-hooks/hooks.rb:49:in `run'
8: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/executable-hooks-1.6.0/lib/executable-hooks/hooks.rb:49:in `each'
7: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/executable-hooks-1.6.0/lib/executable-hooks/hooks.rb:50:in `block in run'
6: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/rubygems-bundler-1.4.5/lib/rubygems_executable_plugin.rb:4:in `block in '
5: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:156:in `require'
4: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:168:in `rescue in require'
3: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/site_ruby/2.6.0/rubygems/core_ext/kernel_require.rb:168:in `require'
2: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/rubygems-bundler-1.4.5/lib/rubygems-bundler/noexec.rb:131:in `'
1: from /Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/rubygems-bundler-1.4.5/lib/rubygems-bundler/noexec.rb:124:in `check'
/Users/zhouxianming/.rvm/rubies/ruby-2.6.3/lib/ruby/gems/2.6.0/gems/rubygems-bundler-1.4.5/lib/rubygems-bundler/noexec.rb:84:in `setup': undefined method `plain_specs' for # (NoMethodError)
一般是Xcode Command Line Tool缺失的原因，可以先执行
xcode-select --install
进行安装。
12、执行以上命令后
Setting up CocoaPods master repo
$ /usr/bin/git clone https://github.com/CocoaPods/Specs.git master --progress
Cloning into 'master'...
remote: Counting objects: 1879515, done.
remote: Compressing objects: 100% (321/321), done.
Receiving objects: 21% (404525/1879515), 73.70 MiB | 22.00 KiB/
然后就是漫长的等待，当然,网络好的情况下会更快
如果一直安装不成功请参考这里
以下一段忽略,直接看 第13步:
要查看文件下载进度的可以另外打开一个终端窗口(快捷键:选中终端按下Command+N组合键)，输入以下两行命令回车执行
cd ~/.cocoapods
du -sh *
执行du -sh *之后会显示已下载的文件大小，可以多次执行来监看下载进度，如果之前还有文件大小，后来变成0了，可能是网络问题，下载已经中断了,需要结束命令并从新执行 pod setup
13、下载安装完成之后可执行下列命令检查是否可用（第一次使用可能要等一会）
pod search AFNetworking
14、CocoaPods的具体使用
新建一个Xcode工程，使用终端cd到工程目录下
创建Podfile文件：
pod init
之后就可以在项目目录里看到一个Podfile文件
打开Podfile文件：
open Podfile
添加：
pod 'AFNetworking'
保存后退出
开始下载：
pod install
CocoaPods版本
pod --version