I started an iOS project last week and decided to use dlib for some features it provides. This blog will keep track of the process.
Compile with dlib
There is an introduction blog about this topic. Getting Started With dlib on iOS
It was very useful but while following it, I still got some problems.
0
Some error about libdlib.a not compiled for arm64.
Solution:
don’t use General iOS Device which uses mac’s architecture. Use simulator or real device.
1
Undefined symbols for architecture arm64:
"_USER_ERROR__missing_dlib_all_source_cpp_file__OR__inconsistent_use_of_DEBUG_or_ENABLE_ASSERTS_preprocessor_directives_", referenced from:
_dlib_check_consistent_assert_usage in DlibWrapper.o
ld: symbol(s) not found for architecture arm64
clang: error: linker command failed with exit code 1 (use -v to see invocation)
Solution: https://stackoverflow.com/questions/37208964/error-including-dlib-library-in-c-project add dlib/all/source.cpp to your project sources list(CXXFILES)
2
jpeglib.h file not found
Initially I tried to look for where the
#ifdef DLIB_JPEG_STATIC
# include "../external/libjpeg/jpeglib.h"
#else
# include <jpeglib.h>
#endif
I thought it was because that I didn’t compile dlib with this DLIB_JPEG_STATIC set. But I was wrong.
Anyway, after about 10 hours try/error, I released that my dlib archive file was in x86_64 architecture. I then went back to the tutorial and read line by line.
After
cmake -G Xcode ..
cmake --build . --config Release
There is a libdlib.a in Release folder. This is not the one I suppose to use. The architecture was by default macos.
I should open the Xcode project in build/dlib_build, change the project setting (not the target setting!), use architecture = arm64, create new schema for release, then run it. Now there is a new folder called /build/dlib_build/Release-iphoneos. Inside it there is a new libdlib.a. This is the one I should use.
hint: at this time the error was actually symbol not found for arm64.... libdlib.a is built for architecture other than arm64... something like that.