现象：iOS app启动的时特别慢，需要半分钟，在terminal中可以看到watchman的错误信息
1、
ERROR: Unknown option --no-pretty
Watchman: watchman--no-pretty get-sockname returned with exit code 1 ERROR: Unknown option --no-pretty
ERROR watchman--no-pretty get-sockname returned with exit code 1 ERROR: Unknown option --no-pretty
Error: watchman--no-pretty get-sockname returned with exit code 1 ERROR: Unknown option --no-pretty
at ChildProcess、(/home/sreejith/projects/sample/node_modules/react-native/node_modules/sane/node_modules/fb-watchman/index.js:194:18)
at emitTwo (events.js:87:13)
at ChildProcess.emit (events.js:172:7)
at maybeClose (internal/child_process.js:817:16)
at Socket.
(internal/child_process.js:319:11)
at emitOne (events.js:77:13)
at Socket.emit (events.js:169:7)
at Pipe._onclose (net.js:469:12)
或者：
2、Watchman: watchman--no-pretty get-sockname returned with exit code 1 ...... NO such file
....
at ChildProcess ....
at emitTwo ....
.....
解决办法：
npm r -g watchman
brew update && brew upgrade
brew uninstall watchman
brew link pcre
brew install --HEAD watchman
如果遇到权限问题 使用命令 sudo chown -R $(whoami):admin /usr/local
