swift 待研备份

https://www.ctolib.com/topics-115290.html

但是还是用到了一个叫做 The Protocol Witness Table (PWT) 的函数表

https://blog.csdn.net/Hello_Hwc/article/details/53147910

https://academy.realm.io/posts/goto-mike-ash-exploring-swift-memory-layout/