[!] The version of CocoaPods used to generate the lockfile (1.9.3) is higher than the version of the

pod install 时 [!] The version of CocoaPods used to generate the lockfile (1.9.3) is higher than the version of the current executable (1.9.1). Incompatibility issues may arise.

pod --version

gem sources --remove https://gems.ruby-china.org/

gem sources -a https://gems.ruby-china.com/

gem source -l

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