https://soooprmx.com/obj-c-nsobject-%ec%97%86%ec%9d%b4-%ec%83%88%eb%a1%9c%ec%9a%b4-%ea%b0%9d%ec%b2%b4%eb%a5%bc-%eb%a7%8c%eb%93%a4%ea%b8%b0/
[Obj-C] NSObject 없이 새로운 객체를 만들기