Undefined symbols for architecture x86_64:"xxxxxx", referenced from:

问题：

Undefined symbols for architecture x86_64:

  "VZNetwork::VZSocket::socket_instance", referenced from:

      VZNetwork::VZSocket::initSocket() in VZSocket.o

ld: symbol(s) not found for architecture x86_64

clang: error: linker command failed with exit code 1 (use -v to see invocation)

解决方案：

socket_instance 变量是静态的，类型是int, 去掉static就可以了