1、OpenSSL-Universal requires CocoaPods version >= "1.9"
podinstall时提示需要把CocoaPods升级到1.9，但是通过brew install CocoaPods，发现安装的版本是1.6.1，brew upgrade CocoaPods 发现版本无法升级，后来查到1.9的版本需要通过gem install -n /usr/local/bin cocoapods --pre才能安装最新的版本
2、Typedef redefinition with different types ('uint8_t' (aka 'unsigned char') vs 'enum clockid_t')
changing iOS Deployment Target of Flipper-Folly Pods to "iOS 9.0", this error disappeared.
3、 'event2/event-config.h' file not found
Flipper-Folly的版本有问题，需要指定版本
use_flipper!修改为use_flipper!({ 'Flipper-Folly' => '2.3.0' })
重新pod install即可
