UIKIT_EXTERN_CLASS 和 UIKIT_EXTERN

最新推荐文章于 2025-06-11 12:00:00 发布

原创最新推荐文章于 2025-06-11 12:00:00 发布 · 5.2k 阅读

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文章标签：

#class #library #linker #reference #security #access

本文探讨了iOS开发中UIKIT_EXTERN_CLASS和UIKIT_EXTERN的含义。这两个宏与Objective-C类的符号可见性相关，影响链接器行为。隐藏类并不完全提供安全性，但直接引用隐藏在库中的类会导致链接错误。因此，如果类设计为对外可用，必须确保其符号可见性正确。

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#ifdef __cplusplus
#define UIKIT_EXTERN            extern "C" __attribute__((visibility ("default")))
#else
#define UIKIT_EXTERN            extern __attribute__((visibility ("default")))
#endif

#define UIKIT_STATIC_INLINE static inline
#define UIKIT_EXTERN_CLASS      __attribute__((visibility("default")))

IOS中经常看到UIKIT_EXTERN_CLASS and UIKIT_EXTERN着2个东西，

不太清楚什么意思，没有baidu什么答案。

google一下

找到这个解释。

http://developer.apple.com/library/mac/#documentation/DeveloperTools/Conceptual/CppRuntimeEnv/Articles/SymbolVisibility.html

下边这一段

When building for x86_64 Mac OS X or for iOS, symbol visibility does affect objective-C classes. Hiding a class is not a security panacea—enterprising developers can access any class with objective-C runtime calls—but if you directly reference a class whose visibility is hidden in a library you link to, you will get a linker error. This means that if a given class is intended to be usable outside the library or executable it's defined in, you need to ensure proper symbol visibility.