错误信息：ld: library not found for -lstdc++.6
报错原因：Xcode10移除了动态库libstdc
修复方法：
需要将libstdc文件复制到下述四个路径下，才能保证模拟器和真机均能正常使用。
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/Library/CoreSimulator/Profiles/Runtimes/iOS.simruntime/Contents/Resources/RuntimeRoot/usr/lib/
/Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk/usr/lib/
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS.sdk/usr/lib/
/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator.sdk/usr/lib/
文件下载地址：
https://download.csdn.net/download/overstep1024/11193547
