iOS中链接混编C＋＋库的编译问题

问题

从新封装画板内核库后，全部的混编文件（.mm）都被打包到了库中，外面应用层代码所有都是OC文件（.m）。这时候编译工程会出现以下链接错误：

Undefined symbols for architecture arm64: "vtable for __cxxabiv1::__vmi_class_type_info", referenced from: ... NOTE: a missing vtable usually means the first non-inline virtual member function has no definition. "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::assign(char const*)", referenced from: ... "___cxa_pure_virtual", referenced from: ... "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::operator=(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from: ... "std::__1::__vector_base_common<true>::__throw_out_of_range() const", referenced from: ... "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::basic_string(std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> > const&)", referenced from: ... "std::terminate()", referenced from: ... "___cxa_guard_release", referenced from: ... "___cxa_guard_abort", referenced from: ... "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::__init(char const*, unsigned long)", referenced from: ... "std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char> >::reserve(unsigned long)", referenced from: ... "___gxx_personality_v0", referenced from: ... ... ld: symbol(s) not found for architecture arm64 clang: error: linker command failed with exit code 1 (use -v to see invocation)

探索

经过网上搜索到以下解决方案

1. 将Build Settings->Apple LLVM7.1-Language中的Compile Sources As修改成According To File Tyle
2. 将Build Settings->Apple LLVM7.1-Language中的Compile Sources As修改成Objective-C++

以上第二个方法对我不适用，修改成所有按**Objective-C++方式编译源文件会出问题。第一个解决方案的话也有问题，因为项目中没有了混编文件（.mm），那么Xcode根本不会调用Objective-C++**编译器，因此链接问题仍是存在。

解决

将项目中的某个OC文件（.m）强行改成后缀为mm，使其成为混编文件。 这种方法也适用于Swift工程，若是Swift也要引用C＋＋的混编库，那么能够增长一个空的混编文件（.mm），该文件不用实现，只是为了欺骗IDE，调出相应编译器完成链接。