Integrating un4seen BASS with Flutter using FFI and getting symbol error - flutter

Question

I'm trying to integrate the BASS audio library from un4seen Developments with Flutter, Google's cross-platform app development environment. I've started a Flutter plugin that can be found here: https://github.com/JimTompkins/flutter_bass. It uses Flutter's FFI (foreign function interface) mechanism and a package called ffigen to convert the bass.h file to generated_bindings.dart.
Here is a snippet from generated_bindings.dart:
int BASS_Init(
int device,
int freq,
int flags,
ffi.Pointer<ffi.Void> win,
ffi.Pointer<ffi.Void> dsguid,
) {
return _BASS_Init(
device,
freq,
flags,
win,
dsguid,
);
}
late final _BASS_InitPtr = _lookup<
ffi.NativeFunction<
BOOL Function(ffi.Int32, DWORD, DWORD, ffi.Pointer<ffi.Void>,
ffi.Pointer<ffi.Void>)>>('_BASS_Init');
late final _BASS_Init = _BASS_InitPtr.asFunction<
int Function(
int, int, int, ffi.Pointer<ffi.Void>, ffi.Pointer<ffi.Void>)>();
It builds (Flutter 3.3, XCode 13) but throws a run-time error when I try to call the BASS_init function:
Failed to lookup symbol '_BASS_Init': dlsym(0x100f61e18, _BASS_Init): symbol not found
I can see the symbol in the libbass.a file using nm -gU libbass.a
Any comments/suggestions welcomed!
Update 2022-09-20:
I added the following frameworks to the Xcode build:
AVFoundation, AudioToolbox, SystemConfiguration, CFNetwork, Accelerate
In Xcode by going to Build Phase-->Link Binary with Libraries-->Add
This did not make any difference i.e. still getting symbol error
I checked that “Enable bitcode” is set to “No” in Xcode under Build Settings-->Build Options.
The search continues...
Updated 2022-09-29:
I got a hint from this Github issue post: use a force_load option to Xcode in the podspec file:
s.pod_target_xcconfig = {'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386', "OTHER_LDFLAGS" => '-force_load ($SRCROOT)/../../../ios/bass24-ios/bass.xcframework/ios-arm64_armv7_armv7s/libbass.a' } s.vendored_libraries = '($SRCROOT)/../../../ios/bass24-ios/bass.xcframework/ios-arm64_armv7_armv7s/libbass.a'
I tried this but now I'm getting a file not found error.
Could not build the precompiled application for the device.
Error (Xcode): File not found:
(/Users/jimtompkins/git/flutter_bass/example/ios/Pods)/../../../ios/bass24-ios/bass.xcframework/ios-arm64_armv7_armv7s/libbass.a
I checked and the file is there:
% ls -als /Users/jimtompkins/git/flutter_bass/example/ios/Pods/../../../ios/bass24-ios/bass.xcframework/ios-arm64_armv7_armv7s/libbass.a
1536 -rw-r--r--# 1 jimtompkins staff 785096 8 Sep 2021 /Users/jimtompkins/git/flutter_bass/example/ios/Pods/../../../ios/bass24-ios/bass.xcframework/ios-arm64_armv7_armv7s/libbass.a
Any hints greatly appreciated!
Update: 2022-09-30: fixed by removing ( ) around the $SRCROOT.
I also found that I needed to add the necessary frameworks to the OTHER_LDFLAGS command in the podspec file. See the Github repo.