Question: Hi I'm trying to run my react native app on mac mini. I can run another app also this app to but when i write `pod install` in terminal it gives this error.

```
1: from /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/specification.rb:1449:in `block in activate_dependencies'

    /System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/2.6.0/rubygems/dependency.rb:311:in `to_specs': Could not find 'ffi' (>= 1.3.0) among 85 total gem(s) (Gem::MissingSpecError)
    Checked in 

'GEM_PATH=/Users/xx/.gem/ruby/2.6.0:/Library/Ruby/Gems/2.6.0:/System/Library/Frameworks/Ruby.framework/Versions/2.6/usr/lib/ruby/gems/2.6.0', execute `gem env` for more information

```

I tryed a lot like this code

```
sudo gem pristine --all,  gem pristine --all

sudo gem install -n /usr/local/bin cocoapods -v 1.8.4

delete and ini pod init/ which gave error
brew reinstall cocoapods
\curl -sSL https://get.rvm.io | bash -s stable --ruby

```

Answer: 
For me, install a new version of ruby resolved this issue.

```
curl -L https://get.rvm.io | bash -s stable
source ~/.rvm/scripts/rvm
rvm list known
rvm install 2.7.2
sudo gem install cocoapods

```
i solved the issue by installing the command line tool for XCode.

Just download the specific CLT from apple website