macos - OSX 中 CFString 的 native utf 编码是什么？

Question

这应该很容易找到，但我似乎无法在任何地方找到它 - 所以如果这是理所当然的，请原谅。 CFString、UTF-16、UTF-8 等中使用的 native UTF 存储是什么？

为什么我要问的是，我正在连接一些lua代码，lua可以处理UTF-8字符串，但是如果我将它们转换为CFSTring，那么如果它在内部使用UTF-16，将会有性能损失？

我查看了 CFStringGetSystemEncoding，它返回 mac roman - 这似乎不正确。

区域设置返回

LANG="en_AU.UTF-8"...

这表明它是 utf-8 但随后是 docs似乎表明它是 16 位的？

蒂亚

Answer 1

有短章“String storage ” 在文档中说它内部可以有各种编码:

Although conceptually CFString objects store strings as arrays of Unicode characters, in practice they often store them more efficiently. The memory a CFString object requires to represent a string could often be less than that required by a simple UniChar array.

最后一段为那些担心额外转化的人提出了一个解决方案:

You can get further control over the backing store of a string with the CFStringCreateMutableWithExternalCharactersNoCopy function. This function creates a reference to a mutable CFString object but allows you to retain full ownership of the Unicode buffer holding the object’s characters; the object itself points to the buffer as its backing store.