先是执行：sudo gem install cocoapods

报错：

ERROR:  Error installing cocoapods:

The last version of activesupport (>= 5.0, < 8) to support your Ruby & RubyGems was 6.1.7.3. Try installing it with `gem install activesupport -v 6.1.7.3` and then running the current command again

activesupport requires Ruby version >= 2.7.0. The current ruby version is 2.6.10.210.

看起来是要更新Ruby版本，所以执行命令：

sudo gem update --system

报错：

ERROR:  While executing gem ... (Errno::EPERM)

    Operation not permitted @ rb_sysopen - /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/bin/gem

应该是没有权限还是什么，然后执行：

sudo gem update -n usrlocalbin --system

成功升级。

接下来安装cocoapods，输入命令：

sudo gem install cocoapods

报错：
 

ERROR:  While executing gem ... (Gem::FilePermissionError)

    You don't have write permissions for the /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/gems/2.6.0 directory.

应该是没有权限还是什么，再试其他方式：

sudo gem install -n /user/local/bin cocoapods

继续报错：

ERROR:  While executing gem ... (Gem::FilePermissionError)

    You don't have write permissions for the /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/gems/2.6.0 directory.

再试：

sudo gem install cocoapods --user-install

搞定:

提示安装成功，但是注意有个WARNING：

You don't have /Users/a1/.local/share/gem/ruby/2.6.0/bin in your PATH,

  gem executables will not run.

这时候执行pod相关命令的时候会提示：

zsh: command not found: pod

我的解决方法：

执行以下命令：（参考：iMac安装pod遇到的问题 - 简书）

export PATH="/Users/xxx/.local/share/gem/ruby/2.6.0/bin":$PATH

其中xxx是你用户文件名，比如我的是a1：

所以就是

export PATH="/Users/a1/.local/share/gem/ruby/2.6.0/bin":$PATH

全部搞定！！