How to determine if an OS X dylib was linked with -flat_namespace

Question

I have a third party OS X dylib that I'm using in my app and don't have easy access to its creator. I'd like to determine if it was linked with -flat_namespace. Is that possible? If so, how?

Answer 1

Run otool -hV on the library. If you don't see TWOLEVEL, then it was linked with -flat-namespace. For example:

twolevel.dylib:
Mach header
      magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
MH_MAGIC_64  X86_64        ALL  0x00       DYLIB     8        672   NOUNDEFS DYLDLINK TWOLEVEL NO_REEXPORTED_DYLIBS

versus

flat.dylib:
Mach header
      magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
MH_MAGIC_64  X86_64        ALL  0x00       DYLIB     8        672 DYLDLINK NO_REEXPORTED_DYLIBS