无法构建 Objective-C 模块“CoreFoundation”

Question

通过 CocoaPods 更新 Firebase 后，我遇到了此问题。

任何帮助是极大的赞赏。

任何高于 4.0.2 的 Firebase 版本都会在 Xcode（版本 10.1）中导致相同的错误。

错误：

Swift 编译器错误

• 找不到“字符串”文件

• 无法构建 Objective-C 模块“CoreFoundation”

已经尝试过：

• 清洁项目

• 手动添加SDK

• 删除级别数据库并手动添加

问题出在哪里？使用 Swift 文件/标头？用leveldb？还是火力基地？

相关（GitHub 上的类似问题，但那里建议的解决方案对我不起作用）：

https://github.com/google/leveldb/issues/515

Xcode 消息：

> <module-includes>:1:9: note: in file included from
> <module-includes>:1:
> #import "Headers/CoreFoundation.h"
>         ^ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator12.1.sdk/System/Library/Frameworks/CoreFoundation.framework/Headers/CoreFoundation.h:43:10:
> note: in file included from
> /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator12.1.sdk/System/Library/Frameworks/CoreFoundation.framework/Headers/CoreFoundation.h:43:
> #include <CoreFoundation/CFBase.h>
>          ^ /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator12.1.sdk/System/Library/Frameworks/CoreFoundation.framework/Headers/CFBase.h:72:10:
> note: in file included from
> /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator12.1.sdk/System/Library/Frameworks/CoreFoundation.framework/Headers/CFBase.h:72:
> #include <Block.h>
>          ^ /Users/Besfort/Desktop/Coding/Xcode - projects/0.1/Pods/leveldb-library/table/Block.h:10:10: note: in file
> included from /Users/Besfort/Desktop/Coding/Xcode -
> projects/0.1/Pods/leveldb-library/table/Block.h:10:
> #include "leveldb/iterator.h"
>          ^ /Users/Besfort/Desktop/Coding/Xcode - projects/0.1/Pods/leveldb-library/include/leveldb/iterator.h:18:10:
> note: in file included from /Users/Besfort/Desktop/Coding/Xcode -
> projects/0.1/Pods/leveldb-library/include/leveldb/iterator.h:18:
> #include "leveldb/slice.h"
>          ^ /Users/Besfort/Desktop/Coding/Xcode - projects/0.1/Pods/leveldb-library/include/leveldb/slice.h:21:10:
> error: 'string' file not found
> #include <string>
>          ^ <unknown>:0: error: could not build Objective-C module 'CoreFoundation'