苹果早在 Xcode 8中 就废弃了libstdc++, 给了开发者两年时间过渡, 如今在Xcode 10 & Xcode 11中已不再支持. 在Build Phases > Link Binary With Libraries 中已经搜不到libstdc++的库了
真机路径：
libstdc++.6.0.9.tbd
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS12.0.sdk/usr/lib
模拟器编译路径：
libstdc++.6.0.9.tbd
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator12.0.sdk/usr/lib
模拟器编运行径：
Xcode 10
libstdc++.6.0.9.dylib
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/Library/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/lib/
Xcode 11
libstdc++.6.0.9.dylib
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Library/Developer/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/lib
链接: https://pan.baidu.com/s/1uMLmbzrc0Osc3T19Gubd_Q 提取码: q58g
