React Native?使用Yarn，?Yarn是Facebook提供的替代npm的工具急波，可以加速node模塊的下載
1. 安裝Yarn:?
npm install -g yarn react-native-cli
2. 設(shè)置國內(nèi)鏡像：
npm config set registry https://registry.npm.taobao.org --global
npm config set disturl https://npm.taobao.org/dist --global
3.?命令,?參考：https://blog.csdn.net/u013233097/article/details/78652728
react-native init projectname
npm install --> yarn
npm install --save react-navigation --> yarn add react-navigation
