ios - Xcode中如何知道Objective-C语言版本

Question

有什么方法可以检查我在我的应用程序中使用的 Objective-C 版本

Answer 1

Objective-C 语言支持级别由用于编译代码的 Clang 版本定义，它本身非常接近 Xcode 的版本。

#if __clang_major__ >= 11
    NSLog(@"My Objective-C language support is what Apple Clang/Xcode 11.x can support.");
    // This language version supports the additional features/fixes written under "Apple Clang Compiler"
    // https://developer.apple.com/documentation/xcode_release_notes/xcode_11_release_notes
    // Notably this version adds Objective-C support to:
    // - `[[clang::no_destroy]]` and `[[clang::always_destroy]]`

#elif __clang_major__ >= 10
    NSLog(@"My Objective-C language support is what Apple Clang/Xcode 10.x can support.");
    // This language version supports the additional features/fixes written under "Apple Clang Compiler"
    // https://developer.apple.com/documentation/xcode_release_notes/xcode_10_release_notes
    // Notably this version adds macro support to:
    // - detect most builtin pseudo-functions with `__has_builtin`

#elif __clang_major__ >= 9
    NSLog(@"My Objective-C language support is what Apple Clang/Xcode 9.x can support.");
    // This language version supports the additional features/fixes written under "Apple LLVM Compiler and Low-Level Tools"
    // https://developer.apple.com/library/archive/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW878
    // Notably this version adds Objective-C support for:
    // - the `@available` language feature

#elif __clang_major__ >= 8
    NSLog(@"My Objective-C language support is what Apple Clang/Xcode 8.x can support.");
    // This language version supports the additional features/fixes written under "Objective-C and C++"
    // https://developer.apple.com/library/archive/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW78
    // Notably this version adds Objective-C support for:
    // - the `@property (class)` language feature

#elif __clang_major__ >= 7
    NSLog(@"My Objective-C language support is what Apple Clang/Xcode 7.x can support.");
    // This language version supports the additional features/fixes written under "Objective-C"
    // https://developer.apple.com/library/archive/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW326
    // Notably this version adds Objective-C support for:
    // - `CF_RETURNS_NOT_RETAINED` and `CF_RETURNS_RETAINED`
    // - `__kindof`
    // - `_Nullable`, `_Nonnull`, and `_Null_unspecified`
    // - Lightweight generics like `NSArray<UIImage *> *` and `NSDictionary<NSString *, NSURL *>`

#elif __clang_major__ >= 6
    NSLog(@"My Objective-C language support is what Apple Clang/Xcode 6.x can support.");
    // This language version supports the additional features/fixes written at:
    // https://developer.apple.com/library/archive/releasenotes/DeveloperTools/RN-Xcode/Chapters/Introduction.html#//apple_ref/doc/uid/TP40001051-CH1-SW453

#else
    NSLog(@"My Objective-C language support is so old that I won't even be allowed to publish this on any App Store nowadays.");

#endif

如果您需要更精确的版本，您也可以使用 __clang_minor__。

只要有可能，建议使用 __has_builtin检查 Objective-C 语言功能的可用性，而不是 __clang_major__ 和 __clang_minor__。

一些值得注意的其他较旧的历史语言功能，您甚至不应该再费心测试可用性了:

• NS_ENUM 和 NS_OPTIONS 已添加到 Xcode 4.5
• NSDictionary 和 NSArray 下标已在 Xcode 4.4/4.5 中添加
• @YES 和 @NO 文字已添加到 Xcode 4.4/4.5
• NSNumber、NSDictionary 和 NSArray 文字已添加到 Xcode 4.4
• @autoreleasepool block 已添加到 Xcode 4.2
• “Objective-C 2.0”是非常古老的东西(Xcode 2.x)

最后，“Modern Objective-C”仅指任何当前可用的 Xcode 对 Objective-C 的支持。

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