SHELL

CocoaPods not installed

$ sudo gem install cocoapods

flutter doctor - CocoaPods installed but not working

curl -L https://get.rvm.io | bash -s stable
rvm install ruby-2.6
rvm use ruby-2.6.5
rvm --default use 2.6.5
sudo gem update
sudo gem install ffi
brew install libffi
sudo gem install cocoapods
pod setup

flutter cocoapods not installed

If with sudo its failing,First download and install brew 
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
step 1 brew install cocoapods
step 2 sudo arch -x86_64 gem install ffi
step 3 arch -x86_64 pod install