【问题标题】:Linking problem in Xcode when using a dependent subproject使用依赖子项目时 Xcode 中的链接问题
【发布时间】:2011-06-30 00:57:13
【问题描述】:

我正在使用 Xcode 编写一个 iPhone 项目,并且我使用了一个外部库。我将Xcode项目文件添加到父目标并调整了头搜索路径并将其设置为父构建目标中的直接依赖。

现在奇怪的事情发生了:我可以打开库并毫无问题地编译它。该库链接到一些框架,例如AVFoundation.framework.

我清理目标并开始构建父项目。在我的构建结果中,我看到它构建了库,但是链接失败并显示以下错误消息:

Undefined symbols:
  "_AVCaptureSessionPresetMedium", referenced from:
      _AVCaptureSessionPresetMedium$non_lazy_ptr in libZXingWidget.a(ZXingWidgetController.o)
     (maybe you meant: _AVCaptureSessionPresetMedium$non_lazy_ptr)
  "_CVPixelBufferGetHeight", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_CVPixelBufferLockBaseAddress", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_AudioServicesPlaySystemSound", referenced from:
      -[ZXingWidgetController presentResultForString:] in libZXingWidget.a(ZXingWidgetController.o)
  "_AudioServicesCreateSystemSoundID", referenced from:
      -[ZXingWidgetController viewWillAppear:] in libZXingWidget.a(ZXingWidgetController.o)
  "_CVPixelBufferUnlockBaseAddress", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_CVPixelBufferGetBaseAddress", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_CVPixelBufferGetBytesPerRow", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_iconv_close", referenced from:
      zxing::qrcode::DecodedBitStreamParser::append(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, unsigned char const*, unsigned long, char const*)in libZXingWidget.a(DecodedBitStreamParser-64E27B33E79CBC52.o)
      zxing::qrcode::DecodedBitStreamParser::append(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, unsigned char const*, unsigned long, char const*)in libZXingWidget.a(DecodedBitStreamParser-64E27B33E79CBC52.o)
  "_OBJC_CLASS_$_AVCaptureVideoPreviewLayer", referenced from:
      objc-class-ref-to-AVCaptureVideoPreviewLayer in libZXingWidget.a(ZXingWidgetController.o)
  "_iconv", referenced from:
      zxing::qrcode::DecodedBitStreamParser::append(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, unsigned char const*, unsigned long, char const*)in libZXingWidget.a(DecodedBitStreamParser-64E27B33E79CBC52.o)
  "_OBJC_CLASS_$_AVCaptureSession", referenced from:
      objc-class-ref-to-AVCaptureSession in libZXingWidget.a(ZXingWidgetController.o)
  "_OBJC_CLASS_$_AVCaptureDevice", referenced from:
      objc-class-ref-to-AVCaptureDevice in libZXingWidget.a(ZXingWidgetController.o)
  "_kCVPixelBufferPixelFormatTypeKey", referenced from:
      _kCVPixelBufferPixelFormatTypeKey$non_lazy_ptr in libZXingWidget.a(ZXingWidgetController.o)
     (maybe you meant: _kCVPixelBufferPixelFormatTypeKey$non_lazy_ptr)
  "_OBJC_CLASS_$_AVCaptureVideoDataOutput", referenced from:
      objc-class-ref-to-AVCaptureVideoDataOutput in libZXingWidget.a(ZXingWidgetController.o)
  "_CVPixelBufferGetWidth", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_AudioServicesDisposeSystemSoundID", referenced from:
      -[ZXingWidgetController dealloc] in libZXingWidget.a(ZXingWidgetController.o)
  "_OBJC_CLASS_$_AVCaptureDeviceInput", referenced from:
      objc-class-ref-to-AVCaptureDeviceInput in libZXingWidget.a(ZXingWidgetController.o)
  "_AVLayerVideoGravityResizeAspectFill", referenced from:
      _AVLayerVideoGravityResizeAspectFill$non_lazy_ptr in libZXingWidget.a(ZXingWidgetController.o)
     (maybe you meant: _AVLayerVideoGravityResizeAspectFill$non_lazy_ptr)
  "_CMSampleBufferGetImageBuffer", referenced from:
      -[ZXingWidgetController captureOutput:didOutputSampleBuffer:fromConnection:] in libZXingWidget.a(ZXingWidgetController.o)
  "_iconv_open", referenced from:
      zxing::qrcode::DecodedBitStreamParser::append(std::basic_string<char, std::char_traits<char>, std::allocator<char> >&, unsigned char const*, unsigned long, char const*)in libZXingWidget.a(DecodedBitStreamParser-64E27B33E79CBC52.o)
  "_AVMediaTypeVideo", referenced from:
      _AVMediaTypeVideo$non_lazy_ptr in libZXingWidget.a(ZXingWidgetController.o)
     (maybe you meant: _AVMediaTypeVideo$non_lazy_ptr)
ld: symbol(s) not found
collect2: ld returned 1 exit status

我可以在父项目中包含所需的框架,但我认为通过在库项目中包含框架,链接就可以了。

我的问题是:我是否必须在父项目中包含我的依赖子项目使用的所有框架以确保正确链接,还是我做错了什么?

感谢您的帮助。

【问题讨论】:

    标签: iphone objective-c xcode build-process


    【解决方案1】:

    确保包含 "CoreMedia.framework","AudioToolbox.framework","CoreGraphics.framework","CoreVideo.framework","AVFoundation.framework","libiconv.dylib" 构建阶段项目中的框架

    【讨论】:

      【解决方案2】:

      如果子项目编译成静态库,是的。

      【讨论】:

      • 我正在编译成一个静态库,因为它是为 iOS 设计的。这真的很不方便。为什么子项目中的链接不够?
      • 静态库本身并没有真正链接到任何东西。只有可执行文件和动态库通过链接过程。我不完全确定 Xcode 如何处理框架引用,但您甚至可能需要引用标准框架才能查看它们的头文件。我相信其他人可以对此给出明确的答案。
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