Undefined symbols for architecture x86_64:
  "_OBJC_CLASS_$_Person", referenced from:
      objc-class-ref in main.o
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

有两个红色叹号并没有在程序上，请问这连哥哥报错是什么意思啊？

请问这两个报错是什么意思啊

xcode上面的报错？

必须ok的啊

哎哟不错哟

不错，好！！！