由于react-native升级到0.42.0，报错：jschelpers/JavaScriptCore.h file not found,根据相关github issues反馈，需将cocoapods升级到1.2.0
- 执行升级cocoapods之后：
sudo gem install cocoapods -v 1.2.0
报错：
ERROR: Could not find a valid gem 'cocoapods' (= 1.2.0) in any repository
ERROR: While executing gem ... (OpenSSL::SSL::SSLError)
hostname "upyun.gems.ruby-china.org" does not match the server certificate
- 在想是不是需要升级下gem，于是执行：
sudo gem update --system
报错：
ERROR: While executing gem ... (OpenSSL::SSL::SSLError)
hostname "upyun.gems.ruby-china.org" does not match the server certificate
- 看来是源路径的问题，修改源路径：
gem sources --remove https://ruby.taobao.org/
gem sources -a https://gems.ruby-china.org
gem更新成功
- 更新cocoapod：
sudo gem install cocoapods
报错：
ERROR: While executing gem ... (Errno::EPERM)
Operation not permitted - /usr/bin/xcodeproj
于是修改语句为：
sudo gem install -n /usr/local/bin cocoapods --pre
升级成功
