因为项目需求，要更新闪验SDK，但是podsearch找不到最新的。于是升级cocoapods
坑1：
报错：zsh: /usr/local/bin/pod: bad interpreter: /System/Library/Frameworks/Ruby.framework/Versions/2.3/usr/bin/ruby: no such file or directory
解决方法：
终端输入：sudo gem install -n /usr/local/bin cocoapods
坑2：执行sudo gem install cocoapods
报错：ERROR: While executing gem ... (Gem::FilePermissionError)
You don't have write permissions for the /usr/bin directory.
解决方案--执行：sudo gem install cocoapods -n /usr/local/bin
安装之后，podsearch
报错：[!] CDN: trunk URL couldn't be downloaded: https://cdn.cocoapods.org/all_pods_versions_1_8_7.txt, error: Net::OpenTimeout
删除~/Library/Caches/CocoaPods下的search_index.json文件
还是不行，podsearch会卡住，等了很久还是报错。
最后找到解决方案：
执行 sudo xcode-select -switch /Applications/Xcode.app/Contents/Developer (-switch 后面加上你的Xcode.app包内容里的Developer的文件夹路径即可)
完美解决，希望能帮到大家。
