关于安装pod时的报错：
To see why this extension failed to compile, please check the mkmf.log which can be found here:
/Library/Ruby/Gems/2.6.0/extensions/universal-darwin-19/2.6.0/ffi-1.15.0/mkmf.log
extconf failed, exit code 1
解决方案：
文件夹前往：
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/include/ruby-2.6.0
所以将20复制粘贴将universal-darwin20文件改成universal-darwin19，如图：
再执行sudo gem install cocoapods
原文链接
https://www.jianshu.com/p/f00be46d77ef
