找到解决方案:

• Objective-C Bridging Header"设置(又名 SWIFT_OBJC_BRIDGING_HEADER)必须在目标级别设置，而不是在项目级别.请务必删除项目级别的设置值.

• The "Objective-C Bridging Header" setting (aka SWIFT_OBJC_BRIDGING_HEADER) must be set at the Target level, and NOT the Project level. Be sure to delete the setting value at the Project level.

(对我来说，这似乎是一个 Xcode 错误，因为我不知道它为什么要修复它).

(to me, it seems like an Xcode bug, since I don't know why it fixes it).