不允许使用swift类的Objective C头文件中定义的Constant.架构armv7的未定义符号 [英] Not allowing to use Constant defined in Objective C header file in swift class. Undefined symbols for architecture armv7

问题描述

我创建了 Objective C Header文件.并在其中添加了一些属性.
我宣布
static NSString* const kColor005C98 = @"005C98";在Constants.h文件

I created Objective C Header file. and added some properties in it.
i declared
static NSString* const kColor005C98 = @"005C98"; in Constants.h file

我在 Bridging-Header 文件中将此文件定义为#import "Constants.h" 现在，当我想在某些 swift 文件中使用此属性kColor005C98时，构建失败，并且我得到

I defined this file in Bridging-Header file as #import "Constants.h" Now when i want to use this property kColor005C98 in some swift file it failed the build and i am getting

体系结构armv7的未定义符号:"_ kColor005C98"，引用自:

Undefined symbols for architecture armv7: "_kColor005C98", referenced from:

我不知道我还需要做什么，所以我不会收到此错误? (我已经在其他目标C 文件中成功使用了此属性，在这种情况下没有问题)

i don't know what else i need to do so i don't get this error? (i have used this property in other objective C file successfully and no issue in that case)

推荐答案

更新:

从Swift 2/Xcode 7及更高版本开始，像这样的静态常量定义

As of Swift 2/Xcode 7 and later, a static constant definition like

static NSString* const kColor005C98 = @"005C98"; // in Constants.h file

导入到Swift中，可以毫无问题地使用.

is imported to Swift and can be used without problems.

(Swift 1.x的旧答案)代码出现时

static NSString* const kColor005C98 = @"005C98"; // in Constants.h file

由 Objective-C 编译器处理，它被视为两件事 合并成一条语句:

is processed by an Objective-C compiler, it is treated as two things combined into one statement:

• 一个变量 declaration ，它引入一个标识符并描述其类型，并且
• 一个变量定义，它实际上实例化/实现了该标识符.

• A variable declaration which introduces an identifier and describes its type, and
• a variable definition which actually instantiates/implements this identifier.

例如 定义与声明之间有什么区别? 很好地说明了声明和 定义.

See for example What is the difference between a definition and a declaration? for a good explanation of the difference between declaration and definition.

Swift编译器仅将该语句视为声明. 因此，该变量未在任何地方定义，从而导致链接器错误.

The Swift compiler treats the statement only as a declaration. Therefore the variable is not defined anywhere, causing the linker error.

要解决该问题，必须将定义移至Objective-C 文件:

To solve the problem, you have to move the definition to an Objective-C file:

// Constants.m:
#import "Constants.h"
NSString * const kColor005C98  = @"005C98";

并将声明更改为extern声明:

// Constants.h:
extern NSString * const kColor005C98;

或者，您只需删除static修饰符即可:

Alternatively, you can just remove the static modifier:

 NSString * const kColor005C98 = @"005C98";

使其与Swift一起使用.缺点是 该行包含在多个Objective-C文件中，所有这些文件 将定义一个全局可见的符号kColor005C98，从而导致 重复符号"链接器错误.

to make it work with Swift. The disadvantage is that when this line is included by multiple Objective-C files, all of them will define a globally visible symbol kColor005C98, causing "duplicate symbol" linker errors.

另一种替代方法是使用宏定义:

#define kColor005C98 @"005C98"

这篇关于不允许使用swift类的Objective C头文件中定义的Constant.架构armv7的未定义符号的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！