Objective-C：如何对一系列字符串常量进行分组？ [英] Objective-C: how to group a series of string constants?

问题描述

我以宏的方式定义了一系列字符串常量，

I defined a series of string constants like below, in macro way,

#define EXT_RESULT_APPID  @"appid"
#define EXT_RESULT_ERROR_CODE  @"errorcode"
#define EXT_RESULT_PROGRESS  @"progress"
...

所有这些常量应该在相同的上下文中使用，所以我想在同一个命名空间中约束它们，我不想让它们全局，只是就像这个帖子所说的那样。

All these constants are supposed to be used in same context, so I'd like to constraint them in a same namespace, and I don't want to make them global, just like what this post said.

另一方面，我可以将所有数字常量放在枚举中，但它不适用于字符串。
然后我怎么能将这些相关的字符串常量分组？

In the other hand, I could put all numeric constants in an enum but it doesn't work for strings. Then how could I group these related string constants?

推荐答案

这是一种方法：

MONExtResult.h

// add __unsafe_unretained if compiling for ARC
struct MONExtResultStruct {
    NSString * const AppID;
    NSString * const ErrorCode;
    NSString * const Progress;
};

extern const struct MONExtResultStruct MONExtResult;

MONExtResult.m

const struct MONExtResultStruct MONExtResult = {
    .AppID = @"appid",
    .ErrorCode = @"errorcode",
    .Progress = @"progress"
};

使用中：

NSString * str = MONExtResult.AppID;

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