cocoapods报错：/usr/local/bin/pod:

使用cocoapods更新第三方库时出现错误（/usr/local/bin/pod: /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby: bad interpreter: No such file or directory）意思就是Ruby的版本与当前系统不适配，最近确实升级了系统到 macOS Catalina 10.15.3

解决方案：

终端更新brew、ruby和cocoapods

1.更新brew

      $ brew update

2.更新完brew，更新ruby

      $ brew install ruby

3.最后开始更新cocoapods

      $ sudo gem install -n /usr/local/bin cocoapods

但是在第二步的时候报错：

Error: The following directories are not writable by your user:
/usr/local/share/man/man3


You should change the ownership of these directories to your user.
  sudo chown -R $(whoami) /usr/local/share/man/man3

大概的意思就是文件权限的问题，如下图：

解决方法：

按顺序终端执行

sudo chown -R whoami:admin /usr/local/bin

sudo chown -R whoami:admin /usr/local/share

完成后就可以继续执行上面的步骤进行更新cocoapods，更新完成后使用cocoapods丝滑般的顺畅。