为什么在我的 Mac 应用程序中出现 link 错误（未定义的符号），因为引用已经在静态库中成功构建并 linked？

Question

我的应用程序使用了一个库，我也有源代码并成功构建。该库使用了一些源代码，从 zxing 到很清楚，它再次发现并解析了所有函数调用。但是当我使用这个库时，我遇到了一些指向那些 zxing 引用的链接器错误（未定义的符号）。似乎不可能，因为该应用程序对该代码一无所知——它被隐藏在库中。如何解决这些错误？

来自Xcode：

Ld DerivedData2/ailhost/Build/Products/Release/ailhost.app/Contents/MacOS/ailhost normal x86_64
    cd /Users/me1/Documents/ailhost_mac/svn/trunk/ailhost
    export MACOSX_DEPLOYMENT_TARGET=10.10
    /Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/clang++ -arch x86_64 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX10.11.sdk -L/Users/me1/Documents/ailhost_mac/svn/trunk/ailhost/DerivedData2/ailhost/Build/Products/Release -L/Users/me1/Documents/ailhost_mac/svn/trunk/ailhost/ailhost -F/Users/me1/Documents/ailhost_mac/svn/trunk/ailhost/DerivedData2/ailhost/Build/Products/Release -filelist /Users/me1/Documents/ailhost_mac/svn/trunk/ailhost/DerivedData2/ailhost/Build/Intermediates/ailhost.build/Release/ailhost.build/Objects-normal/x86_64/ailhost.LinkFileList -Xlinker -rpath -Xlinker @executable_path/../Frameworks -mmacosx-version-min=10.10 -stdlib=libstdc++ -fobjc-arc -fobjc-link-runtime -lboost_system-mt -lboost_thread-mt -lSLABHIDtoUART -framework Accelerate -lProcessor -Xlinker -dependency_info -Xlinker /Users/me1/Documents/ailhost_mac/svn/trunk/ailhost/DerivedData2/ailhost/Build/Intermediates/ailhost.build/Release/ailhost.build/Objects-normal/x86_64/ailhost_dependency_info.dat -o /Users/me1/Documents/ailhost_mac/svn/trunk/ailhost/DerivedData2/ailhost/Build/Products/Release/ailhost.app/Contents/MacOS/ailhost

Undefined symbols for architecture x86_64:
  "zxing::DecodeHints::DecodeHints()", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::BinaryBitmap::BinaryBitmap(zxing::Ref<zxing::Binarizer>)", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::HybridBinarizer::HybridBinarizer(zxing::Ref<zxing::LuminanceSource>)", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::GreyscaleLuminanceSource::GreyscaleLuminanceSource(zxing::ArrayRef<char>, int, int, int, int, int, int)", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::Result::getResultPoints()", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::Result::getText()", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::qrcode::QRCodeReader::QRCodeReader()", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
  "zxing::Exception::deleteMessage()", referenced from:
      zxing::Exception::~Exception() in libProcessor.a(Processor.o)
  "zxing::Exception::copy(char const*)", referenced from:
      zxing::Exception::Exception(zxing::Exception const&) in libProcessor.a(Processor.o)
  "zxing::String::getText() const", referenced from:
      Processor::processQRCodeInternal(int, int, int, int) in libProcessor.a(Processor.o)
ld: symbol(s) not found for architecture x86_64
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Answer 1

已修复。问题是 zxing 文件夹中的文件没有被编译到库中，因为文件夹 ("zxing") 和任何文件都不是目标的一部分。我通过仔细检查 "Build Settings" 下的 "Compile Sources" 验证了这一点。（令人恼火的是，当你构建一个静态库时，当文件实际上 not 内置到生成的二进制文件中时，它不会向你显示任何编译错误。）为了我温和的读者的利益，这是怎么发生的是当我右键单击 Xcode 中的主项目文件夹并选择 "Add files to ..." 然后浏览并选择具有所需源的文件夹 ("zxing") 我按原样使用设置， "Create folder references" 被选中。我删除了文件夹然后重新添加，但第二次选择了 "Create Groups"（见附图）。瞧！根据需要将文件添加到目标中。然后构建静态库时没有问题（和以前一样）只有当我实际将我的应用程序 link 放到库中时我才没有未定义的符号错误。

为什么在我的 Mac 应用程序中出现 link 错误（未定义的符号），因为引用已经在静态库中成功构建并 linked？

Why link errors (Undefined symbols) in my Mac app for references that already built and linked successfully in the static library?

c++

macos

cocoa

clang

linker-errors