Swift语法3.03(类型Types)

https://www.jianshu.com/p/839f9bc4b9a3

https://developer.apple.com/library/content/documentation/Swift/Conceptual/Swift_Programming_Language/Generics.html#//apple_ref/doc/uid/TP40014097-CH26-ID179

https://theswiftpost.co/generics-swift-4/

https://blog.csdn.net/crazyeveryday/article/details/46490149

swift 类型备份

原文：https://www.cnblogs.com/feng9exe/p/9102761.html