https://learnblockchain.cn/article/2077
把上面代码复制到remix里后,报错信息为:
DeclarationError: Undeclared identifier. _registerInterface(IERC721Receiver.onERC721Received.selector);
注册interface后.为什么还是报错?
该怎么理解registerInterface?
怎么写才是对的?