npm install -g ios-deploy 失败问题的解决方法

当使用Cordova或ionic命令行时，
npm install -g iOS-deploy 

或sudo npm install -g ios-deploy 都报错，
如：
npm WARN lifecycle ios-deploy@1.8.5~preinstall: cannot run in wd %s %s (wd=%s) ios-deploy@1.8.5 ./src/scripts/check_reqs.js && xcodebuild /usr/local/lib/node_modules/.staging/ios-deploy-298c9491
npm ERR! Darwin 15.3.0
npm ERR! argv "/usr/local/bin/node" "/usr/local/bin/npm" "install" "-g" "ios-deploy"
npm ERR! node v5.8.0
npm ERR! npm  v3.7.3
npm ERR! path /usr/local/lib/node_modules/ios-deploy/build/Release/ios-deploy
npm ERR! code ENOENT
npm ERR! errno -2
npm ERR! syscall chmod

npm ERR! enoent ENOENT: no such file or directory, chmod '/usr/local/lib/node_modules/ios-deploy/build/Release/ios-deploy'
npm ERR! enoent ENOENT: no such file or directory, chmod '/usr/local/lib/node_modules/ios-deploy/build/Release/ios-deploy'
npm ERR! enoent This is most likely not a problem with npm itself
npm ERR! enoent and is related to npm not being able to find a file.
npm ERR! enoent 

解决问题方法在 https://github.com/phonegap/ios-deploy/issues/188 可以找到，其实就是：
sudo npm install -g ios-deploy --unsafe-perm=true

这次倒给出了提示：

!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

!!!! WARNING: You are on OS X 10.11 El Capitan, you may need to add the

!!!! WARNING:   `--unsafe-perm=true` flag when running `npm install`

!!!! WARNING:   or else it will fail.

!!!! WARNING: link:

!!!! WARNING:   https://github.com/phonegap/ios-deploy#os-x-1011-el-capitan
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!