agisilaos

You tried to install cocoapods on your mac and you got an error exactly like this one? 
ERROR: Could not find a valid gem 'cocoapods' (>= 0), here is why:
Unable to download data from https://rubygems.org/ - SSL_connect returned=1 errno=0 state=SSLv3 read server certificate B: certificate verify failed (https://s3.amazonaws.com/production.s3.rubygems.org/latest_specs.4.8.gz)

I had to get pass this error and I was asking myself: Why I couldn't download CocoaPods and what's the error is about?
After a lot of research, it is all about the certificate. You can solve this by updating the certificate.

		rvm osx-ssl-certs update all

After that you need to think and update the rubygems to the latest version:

agisilaos

Fixing npm On Mac OS X for Homebrew Users

Installing node through Homebrew can cause problems with npm for globally installed packages. To fix it quickly, use the solution below. An explanation is also included at the end of this document.

Solution

This solution fixes the error caused by trying to run npm update npm -g. Once you're finished, you also won't need to use sudo to install npm modules globally.

Before you start, make a note of any globally installed npm packages. These instructions will have you remove all of those packages. After you're finished you'll need to re-install them.

agisilaos

swift4Targets = ['Target-1','Target-2','Target-3']
post_install do |installer|
    installer.pods_project.targets.each do |target|
        target.build_configurations.each do |config|
            if swift4Targets.include? target.name
                config.build_settings['SWIFT_VERSION'] = '4'
            else
                config.build_settings['SWIFT_VERSION'] = '3.2'
            end
        end