Undefined symbols for architecture x86_64:

"_OBJC_CLASS_$_The49DayPersonalFullscreenGiftModel", referenced from:

objc-class-ref in The49DayPersonalRoomGiftModel.o

ld: symbol(s) not found for architecture x86_64

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

错因:忘记写实现文件了