要-lobjc还是不要-lobjc？

Question

GCC手册说:

file.m
    Objective-C source code. Note that you must link with thelibobjc
    library yo make an Objective-C program work.

和:

-lobjc
    You need this special case of the-loption in order to link an
    Objective-C or Objective-C++ program.

但是,我可以简单地成功编译一个程序:

$ cc prg.m -framework Foundation

当您包含框架时,它是链接器默认值吗？如果是这样,它在哪里记录？该程序无论如何都会链接:

$ otool -L a.out
a.out:
        /System/Library/Frameworks/Foundation.framework/.../Foundation (...)
        /usr/lib/libSystem.B.dylib (...)
    --> /usr/lib/libobjc.A.dylib (...)
        /System/Library/Frameworks/CoreFoundation.f...k/.../CoreFoundation (...)

Answer 1

这是因为Foundation框架已经与之相关联libobjc.

所以在OSX上,-lobjc只有在你没有与Foundation框架链接时才需要选项(这是非常罕见的).