Apple Mach-O linker error: Undefined symbols for architecture armv7 Google Protobuf

Question

I've been working on a project that contains two parts:

1. A Cocoa Touch Static Library (.framework)
2. A Demo application that uses my (.framework) Static Library

I have learned that any .framework that is added to my .framework (i.e., opencv2.framework) must also be added to my Demo application. I've also learned that the Build Settings for Architectures must be the same and the Build Settings Search Paths must be set.

Happy as can be, I've been building and using my .framework in my Demo application for quite some time. Recently, I've added Google Protocol Buffers to my .framework.

1. My .framework is compiling and all seems well in the .framework.
2. Of course, my Demo application wasn't very happy.

So now I've added the libprotobuf-lite.a to my Demo application and added the path to the Header files in the Header Search Paths.

This should do the trick. But instead, I receive the following errors and thus far have not been able to find an answer. Here is the error log:

Undefined symbols for architecture armv7:
  "vtable for google_public::protobuf::Message", referenced from:
      google_public::protobuf::Message::Message() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  NOTE: a missing vtable usually means the first non-inline virtual member function has no definition.
  "typeinfo for google_public::protobuf::Message", referenced from:
      typeinfo for message::FtypeMessage in Test-Remote-iOS-Aggregate(ftype.pb.o)
      message::FtypeMessage const* google_public::protobuf::internal::dynamic_cast_if_available<message::FtypeMessage const*, google_public::protobuf::Message const*>(google_public::protobuf::Message const*) in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::GetTypeName() const", referenced from:
      vtable for message::FtypeMessage in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::InitializationErrorString() const", referenced from:
      vtable for message::FtypeMessage in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::SpaceUsed() const", referenced from:
      vtable for message::FtypeMessage in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::ReflectionOps::Merge(google_public::protobuf::Message const&, google_public::protobuf::Message*)", referenced from:
      message::FtypeMessage::MergeFrom(google_public::protobuf::Message const&) in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::WireFormat::VerifyUTF8StringFallback(char const*, int, google_public::protobuf::internal::WireFormat::Operation)", referenced from:
      google_public::protobuf::internal::WireFormat::VerifyUTF8String(char const*, int, google_public::protobuf::internal::WireFormat::Operation) in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "_OBJC_CLASS_$_CVImageConverter", referenced from:
      objc-class-ref in Test-Remote-iOS-Aggregate(IDMessageCommand.o)
  "google_public::protobuf::UnknownFieldSet::ClearFallback()", referenced from:
      google_public::protobuf::UnknownFieldSet::Clear() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::DiscardUnknownFields()", referenced from:
      vtable for message::FtypeMessage in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::WireFormat::ComputeUnknownFieldsSize(google_public::protobuf::UnknownFieldSet const&)", referenced from:
      message::FtypeMessage::ByteSize() const in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::WireFormat::SerializeUnknownFields(google_public::protobuf::UnknownFieldSet const&, google_public::protobuf::io::CodedOutputStream*)", referenced from:
      message::FtypeMessage::SerializeWithCachedSizes(google_public::protobuf::io::CodedOutputStream*) const in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::MessageFactory::InternalRegisterGeneratedFile(char const*, void (*)(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&))", referenced from:
      message::protobuf_AddDesc_ftype_2eproto() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::WireFormat::SkipField(google_public::protobuf::io::CodedInputStream*, unsigned int, google_public::protobuf::UnknownFieldSet*)", referenced from:
      message::FtypeMessage::MergePartialFromCodedStream(google_public::protobuf::io::CodedInputStream*) in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::UnknownFieldSet::MergeFrom(google_public::protobuf::UnknownFieldSet const&)", referenced from:
      message::FtypeMessage::MergeFrom(message::FtypeMessage const&) in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::GeneratedMessageReflection::GeneratedMessageReflection(google_public::protobuf::Descriptor const*, google_public::protobuf::Message const*, int const*, int, int, int, google_public::protobuf::DescriptorPool const*, google_public::protobuf::MessageFactory*, int)", referenced from:
      message::protobuf_AssignDesc_ftype_2eproto() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::~Message()", referenced from:
      message::FtypeMessage::FtypeMessage() in Test-Remote-iOS-Aggregate(ftype.pb.o)
      message::FtypeMessage::~FtypeMessage() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::UnknownFieldSet::UnknownFieldSet()", referenced from:
      message::FtypeMessage::FtypeMessage() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::CheckTypeAndMergeFrom(google_public::protobuf::MessageLite const&)", referenced from:
      vtable for message::FtypeMessage in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::DescriptorPool::generated_pool()", referenced from:
      message::protobuf_AssignDesc_ftype_2eproto() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::DescriptorPool::InternalAddGeneratedFile(void const*, int)", referenced from:
      message::protobuf_AddDesc_ftype_2eproto() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::Message::SerializeToOstream(std::__1::basic_ostream<char, std::__1::char_traits<char> >*) const", referenced from:
      message::TestMessaging::ftypeMessage(void const*, unsigned long) in Test-Remote-iOS-Aggregate(TestMessaging.o)
  "google_public::protobuf::MessageFactory::InternalRegisterGeneratedMessage(google_public::protobuf::Descriptor const*, google_public::protobuf::Message const*)", referenced from:
      message::(anonymous namespace)::protobuf_RegisterTypes(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::internal::WireFormat::SerializeUnknownFieldsToArray(google_public::protobuf::UnknownFieldSet const&, unsigned char*)", referenced from:
      message::FtypeMessage::SerializeWithCachedSizesToArray(unsigned char*) const in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::DescriptorPool::FindFileByName(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&) const", referenced from:
      message::protobuf_AssignDesc_ftype_2eproto() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::MessageFactory::generated_factory()", referenced from:
      message::protobuf_AssignDesc_ftype_2eproto() in Test-Remote-iOS-Aggregate(ftype.pb.o)
  "google_public::protobuf::UnknownFieldSet::~UnknownFieldSet()", referenced from:
      message::FtypeMessage::FtypeMessage() in Test-Remote-iOS-Aggregate(ftype.pb.o)
      message::FtypeMessage::~FtypeMessage() in Test-Remote-iOS-Aggregate(ftype.pb.o)
ld: symbol(s) not found for architecture armv7
clang: error: linker command failed with exit code 1 (use -v to see invocation)

Any ideas on what could be the likely issue here?

Thank you.

Answer 1

It looks like the linker is not running on your .framework, and that the .proto files were built for a full libprotobuf instead of libprotobuf-lite.

Try adding a fat libprotobuf.a to your app's framework folder and see if it finds the symbols.

As a side note, you also have another error in there you didn't mention: "_OBJC_CLASS_$_CVImageConverter", referenced from: objc-class-ref in Test-Remote-iOS-Aggregate(IDMessageCommand.o)

Not sure how to fix that one without seeing your code.