Objective-C in，out，inout，byref，byval，..等.这些是什么? [英] Objective-C in,out,inout,byref,byval, .. and so on. What are they?

问题描述

我在阅读@encoding的Objective-C手册时发现了一些陌生的东西.

I discovered something unfamiliar while reading Objective-C manual for @encoding.

Table 6-2  Objective-C method encodings
Code Meaning
r    const
n    in
N    inout
o    out
O    bycopy
R    byref
V    oneway

我唯一知道的是oneway.其他是什么?

The only thing I know is oneway. What are the others?

推荐答案

这些是分布式对象使用的方法参数和返回值的注释.我之所以说是，是因为显然苹果的文档中再也没有这些迹象了. "Objective-C编程语言"文档中曾经有一个远程消息传递"部分，但分布式对象编程主题"文档中仍然引用了该部分.

Those are annotations for method parameters and return values which were used by Distributed Objects. I say were because apparently there’s no sign of them in Apple’s documentation any longer. There used to be a Remote Messaging section in The Objective-C Programming Language document, which is still referenced by the Distributed Objects Programming Topics document.

• 输入:参数仅是输入参数，以后将不再引用
• 输出:参数仅是输出参数，用于通过引用返回值
• inout:参数既是输入参数又是输出参数
• const :(指针)参数是常量
• bycopy:，而不是使用代理/NSDistantObject，而是传递或返回对象的副本
• byref :使用代理对象(默认)

• in: argument is an input argument only and won’t be referenced later
• out: argument is an output argument only, used to return a value by reference
• inout: argument is both an input and output argument
• const: the (pointer) argument is constant
• bycopy: instead of using a proxy/NSDistantObject, pass or return a copy of the object
• byref: use a proxy object (default)

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