CocoaPods安装出现SSL verification error

在安装CocoaPods出现了以下问题:

ERROR: SSL verification error at depth 1: unable to get local issuer certificate (20)
ERROR: You must add /C=IL/O=StartCom Ltd./OU=Secure Digital Certificate Signing/CN=StartCom Certification Authority to your local trusted store
ERROR: SSL verification error at depth 2: self signed certificate in certificate chain (19)
ERROR: Root certificate is not trusted (/C=US/O=GeoTrust Inc./CN=GeoTrust Global CA)

出现这个问题的原因主要是Ruby环境需要2.2版本以上，所以要更新Ruby环境。

更新Ruby环境
首先要安装 Homebrew 终端输入这条命令即可 /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
1.安装rvm $ curl -L get.rvm.io | bash -s stable
2.装载rvm $ source ~/.rvm/scripts/rvm
3.安装2.3.0版本ruby $ rvm install 2.3.0
4.将2.3.0设为默认 $ rvm use 2.3.0 --default