mac版本：
执行flutter doctor 显示cocoapods已被安装，但是不能用(not working)，于是我根据安装指令安装cocoapods，但是安装错误，显示以下报错
curl: (7) Failed to connect to raw.githubusercontent.com port 443: Connection refused
1.打开网站https://www.ipaddress.com/，查询一下 raw.githubusercontent.com对应的IP 地址
2.终端输入sudo vi /etc/hosts，来进行编辑（最新版本没有权限修改hosts文件），输入i进入编辑状态，输入以下内容，然后按esc，最后输入:wq进行保存
199.232.96.133 raw.githubusercontent.com
3.终端输入安装执行，安装 Homebrew
/bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install.sh)"
4.终端输入
sudo gem install -n /usr/local/bin cocoapods
然后再次输入flutter doctor
终端输入
sudo xcode-select --switch /Applications/Xcode.app/Contents/Developer
sudo xcodebuild -runFirstLaunch
解决方法：参考https://blog.csdn.net/qq_43531694/article/details/106862753