First install Brew on your MAC
- Setup Brew: `ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"`
- `brew update`
- `brew tap homebrew/dupes`
- `brew tap homebrew/php`
- Install PHP 7.0.+ `brew install php70`
- Install `mcrypt`: `brew install mcrypt php70-mcrypt`
- Finally, install composer: `brew install composer`
Now if you run `$ php -v`, you will get `PHP 5.5` or something.
This is the default PHP version that is shipped with OSX and cannot be removed.
You just need to edit your path to ensure that `PHP 7.0` is picked up.
`export PATH="$(brew --prefix homebrew/php/php70)/bin:$PATH"`
To debug any issue with any package, you can run `brew info php70` etc.
Also, if you are getting seemingly unrelated errors, make sure to update bash/zsh: `brew upgrade bash` and `brew upgrade zsh`.
If everything is setup correctly, running `$ php -v` should give you 7.0.+.