我首先使Firebase Auth代码工作，一旦添加了Firestore，则添加了数据功能，一切都崩溃了。这是我的错误信息：
> 2018-06-22 00:31:29.238585-0400 Student Council App[4808:1902875]
> [Accessibility] ****************** Loading GAX Client Bundle
> ****************
> 2018-06-22 00:31:29.324018-0400 Student Council App[4808:1902933] 4.11.0 - [Firebase/Core][I-COR000003] The default
> Firebase app has not yet been configured. Add `[FIRApp configure];`
> (`FirebaseApp.configure()` in Swift) to your application
> initialization. Read more: --a link--.
> 2018-06-22 00:31:29.325455-0400 Student Council App[4808:1902875] *** Terminating app due to uncaught exception
> 'FIRAppNotConfiguredException', reason: 'Failed to get FirebaseApp
> instance. Please call FirebaseApp.configure() before using Firestore' …