Mac OS

Install icu4c version 64 with Homebrew

download the homebrew core first 

git clone https://github.com/Homebrew/homebrew-core.git
 

check current installed version 

brew list --versions icu4c

 

1) cd to Homebrew's formula directory

cd $(brew --prefix)/Homebrew/Library/Taps/homebrew/homebrew-core/Formula

2) Find desired commit (version 63 for icu4c) to checkout

git log --follow icu4c.rb

3) Checkout to a new branch