React Native出现"Native module cannot be null"问题

经查跟PushNotification有关，需要手动完成Linking。
两步解决此问题：

• 配置Linking Libraries:https://facebook.github.io/react-native/docs/linking-libraries-ios.html#manual-linking
• 配置PushNotificationIOS:
  https://facebook.github.io/react-native/docs/pushnotificationios.html

参考

https://github.com/facebook/react-native/issues/5612