cmake编译IOS报错提示，unknown type name 'Protocol'

Question

/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObjCRuntime.h:500:19: error:
unknown type name 'NSString'
FOUNDATION_EXPORT NSString *NSStringFromClass(Class aClass);
^
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObjCRuntime.h:501:53: error:
unknown type name 'NSString'
FOUNDATION_EXPORT Class _Nullable NSClassFromString(NSString *aClassName);
^
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObjCRuntime.h:503:19: error:
unknown type name 'NSString'
FOUNDATION_EXPORT NSString *NSStringFromProtocol(Protocol *proto) API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
^
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObjCRuntime.h:503:50: error:
unknown type name 'Protocol'
FOUNDATION_EXPORT NSString *NSStringFromProtocol(Protocol *proto) API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
^
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS13.4.sdk/System/Library/Frameworks/Foundation.framework/Headers/NSObjCRuntime.h:504:19: error:
unknown type name 'Protocol'
FOUNDATION_EXPORT Protocol * _Nullable NSProtocolFromString(NSString *namestr) API_AVAILABLE(macos(10.5), ios(2.0), watchos(2.0), tvos(9.0));
^

Answer 1

https://blog.csdn.net/late_in_autumn/article/details/38292415