swift - Swift 中的哪些值类型支持写时复制？

Question

我阅读了有关 Swift 中 Array 的写时复制实现 here .

Arrays, like all variable-size collections in the standard library, use copy-on-write optimization. Multiple copies of an array share the same storage until you modify one of the copies. When that happens, the array being modified replaces its storage with a uniquely owned copy of itself, which is then modified in place. Optimizations are sometimes applied that can reduce the amount of copying.

我想知道您是否知道哪种结构支持写时复制。

Answer 1

写入时复制支持 String 和所有集合类型 - Array、Dictionary 和 Set。

除此之外，编译器可以自由优化任何结构访问并有效地为您提供写时复制语义，但不能保证。