在執行pod 操作時提示一下錯誤，或者在安裝pod時提示
Ignoring ffi-1.15.5 because its extensions are not built. Try: gem pristine ffi --version 1.15.5

根據后面的提示前面添加sudo

sudo gem pristine ffi --version 1.15.5

正常輸出：

Ignoring ffi-1.15.5 because its extensions are not built. Try: gem pristine ffi --version 1.15.5
Restoring gems to pristine condition...
Building native extensions. This could take a while...
Restored ffi-1.15.5

如果出現：

Ignoring ffi-1.15.5 because its extensions are not built. Try: gem pristine ffi --version 1.15.5
ERROR:  While executing gem ... (Gem::FilePermissionError)
   You don't have write permissions for the /Library/Ruby/Gems/2.6.0 directory.

可以根據下面地址更改系統的權限

https://blog.csdn.net/SharkToping/article/details/79464581

更改后權限后

sudo gem update --system

根據提示輸入密碼,提示類似的內容。

Ignoring ffi-1.15.5 because its extensions are not built. Try: gem pristine ffi --version 1.15.5
Latest version already installed. Done.

再次執行，出現最開始提到的內容，在嘗試執行pod命令

sudo gem pristine ffi --version 1.15.5