https://ios.nobady.cn/Foundation.html#_7-synthesize%E5%92%8C-dynamic%E5%88%86%E5%88%AB%E6%9C%89%E4%BB%80%E4%B9%88%E4%BD%9C%E7%94%A8%EF%BC%9F 你这个粘贴错了吧
