iOS 安装cocoapods报错ERROR: While executing gem

安装指令

sudo gem install cocoapods

报错信息如下：

ERROR:  SSL verification error at depth 2: unable to get local issuer certificate (20)
ERROR:  You must add /C=US/O=VeriSign, Inc./OU=Class 3 Public Primary Certification Authority to your local trusted store
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)
ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted - /usr/bin/pod

解决方法如下：

sudo gem install -n /usr/local/bin cocoapods

OR

sudo gem install -n /usr/local/bin GEM_NAME_HERE