How to load xcframework

[quetool]

Hello! This is just a request for help. I am creating an xcframework following your guideline here https://cjycode.com/flutter_rust_bridge/manual/integrate/library/platform-setup/ios-and-macos but I'm not being able to load it.

Important note: I'm writing a flutter plugin that then is installed as dependency for apps.

This is what I have generated in iOS/ folder of the plugin:

As you can see I have Frameworks/libyttrium.framework, which is what I set in the podfile:

Pod::Spec.new do |s|
  s.name                = 'yttrium_dart'
  s.version             = '0.8.36'
  s.summary             = '4337 implementation'
  s.description         = '4337 implementation and Chain Abstraction'
  s.homepage            = 'https://reown.com'
  s.license             = { :file => '../LICENSE' }
  s.author              = { 'Reown' => 'mobile@reown.com' }
  s.source              = { :git => 'https://github.com/reown-com/yttrium.git', :tag => s.version.to_s }
  s.source_files        = 'Classes/**/*'
  s.vendored_frameworks = 'Frameworks/libyttrium.framework'
  s.dependency 'Flutter'
  s.platform            = :ios, '13.0'

  # Flutter.framework does not contain a i386 slice.
  s.pod_target_xcconfig = {
    'DEFINES_MODULE' => 'YES',
    'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386',
    'LD_RUNPATH_SEARCH_PATHS' => '$(inherited) @executable_path/Frameworks',
  }
  s.swift_version = '5.0'

  # If your plugin requires a privacy manifest, for example if it uses any
  # required reason APIs, update the PrivacyInfo.xcprivacy file to describe your
  # plugin's privacy impact, and then uncomment this line. For more information,
  # see https://developer.apple.com/documentation/bundleresources/privacy_manifest_files
  # s.resource_bundles = {'yttrium_dart_privacy' => ['Resources/PrivacyInfo.xcprivacy']}
end

This is how I load it from Dart side:

if (Platform.isAndroid) {
  // Locate the native library file
  final yttrium = ExternalLibrary.open('libyttrium.so');
  // Initialize the Rust library
  await frb.YttriumDart.init(externalLibrary: yttrium);
} else if (Platform.isIOS) {
  // Initialize the Rust library
  await frb.YttriumDart.init();
} else {
  throw 'Yttrium not yet supported on ${Platform.localeName}';
}

I tried different combinations (included ExternalLibrary.process(iKnowHowToUseIt: true)) for iOS but when running the app this is what I see every time:

Failed to load dynamic library 'yttrium.framework/yttrium': dlopen(yttrium.framework/yttrium, 0x0001): tried: 'yttrium.framework/yttrium' (no such file), '/private/preboot/Cryptexes/OSyttrium.framework/yttrium' (no such file), '/private/var/containers/Bundle/Application/BC45AAAD-DD77-44E8-BD27-DCDA14580D16/Runner.app/yttrium.framework/yttrium' (no such file), '/usr/lib/swift/yttrium.framework/yttrium' (no such file, not in dyld cache), '/private/preboot/Cryptexes/OS/usr/lib/swift/yttrium.framework/yttrium' (no such file), '/private/var/containers/Bundle/Application/BC45AAAD-DD77-44E8-BD27-DCDA14580D16/Runner.app/Frameworks/yttrium.framework/yttrium' (no such file), '/private/var/containers/Bundle/Application/BC45AAAD-DD77-44E8-BD27-DCDA14580D16/Runner.app/Frameworks/yttrium.framework/yttrium' (no such file), '/usr/lib/yttrium.framework/yttrium' (no such file, not in dyld cache), 'yttrium.framework/yttrium' (no such file)

[quetool]

When I try .process() or final yttrium = ExternalLibrary.open('yttrium_dart.framework/yttrium_dart'); this is what I see:

flutter: Invalid argument(s): Invalid argument(s): Failed to lookup symbol 'frb_get_rust_content_hash': dlsym(RTLD_DEFAULT, frb_get_rust_content_hash): symbol not found
flutter: This is often because the Rust library is not loaded correctly.
flutter: Debug information of the external library: by process()
flutter: Original stack trace: #0      DynamicLibrary.lookup (dart:ffi-patch/ffi_dynamic_library_patch.dart:33:70)
flutter: #1      MultiPackageCBinding._frb_get_rust_content_hashPtr (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart:327:56)
flutter: #2      MultiPackageCBinding._frb_get_rust_content_hashPtr (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart)
flutter: #3      MultiPackageCBinding._frb_get_rust_content_hash (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart:330:7)
flutter: #4      MultiPackageCBinding._frb_get_rust_content_hash (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart)
flutter: #5      MultiPackageCBinding.frb_get_rust_content_hash (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart:323:12)
flutter: #6      GeneralizedFrbRustBinding.getRustContentHash (package:flutter_rust_bridge/src/generalized_frb_rust_binding/_io.dart:69:23)
flutter: #7      BaseEntrypoint._sanityCheckContentHash (package:flutter_rust_bridge/src/main_components/entrypoint.dart:106:35)
flutter: #8      BaseEntrypoint.initImpl (package:flutter_rust_bridge/src/main_components/entrypoint.dart:52:5)
flutter: #9      YttriumDart.init (package:yttrium_dart/generated/frb_generated.dart:31:20)
flutter: #10     YttriumClient.init (package:yttrium_dart/yttrium_dart_client.dart:39:31)
flutter: #11     ChainAbstraction.init (package:reown_walletkit/chain_abstraction/chain_abstraction.dart:16:22)
flutter: <asynchronous suspension>
flutter: #12     ReownWalletKit.init (package:reown_walletkit/walletkit_impl.dart:129:5)
flutter: <asynchronous suspension>
flutter: #13     WalletKitService.init (package:reown_walletkit_wallet/dependencies/walletkit_service.dart:132:5)
flutter: <asynchronous suspension>
flutter: #14     _MyHomePageState.initialize (package:reown_walletkit_wallet/main.dart:158:5)
flutter: <asynchronous suspension>
flutter:

I see the xcframeworks packaged during build time here

So I'm assuming everything is fine on the package side...

[fzyzcjy]

Hi, it is suggested to use https://cjycode.com/flutter_rust_bridge/quickstart to integrate, which would be easier to use.

[quetool]

Hello @fzyzcjy, what do you mean? I already went through that, in fact I have all up and running in debug mode. It's also working if I use pure dylib. But since App Store keeps rejecting it with this error...

I'm assuming they are not liking the pure dylib way so I'm trying the xcframework way...

[fzyzcjy]

Hmm, other people using the approach in quickstart (i.e. cargokit) does not discuss this before. So maybe we can ask in Cargokit repo about this issue.

Also, it seems the error requires using latest Xcode, could you please upgrade and try whether it works

[quetool]

The error message from App Store Connect is sh*t honestly, I'm using latest Xcode since long ago 🤣
But since they mention swift support I'm assuming they don't like the embedded dylib. Also I was uploading binaries just fine before this.

Besides apple error message, I think I just need to know how you load the xcframework (or static lib .a) from dart side since apparently I'm not doing it properly.

[fzyzcjy]

Ah I see... I am using my own infra written manually, because at that time there is no Cargokit. But I think cargokit should work (either directly or with minor bugfixes), because both no frb users mention this issue before, and other apps using libs using cargokit also do not mention this.

[quetool]

Can you tell me how you load it from Dart side? I mean, I suppose you still need to load it, right?

I'm referring about these lines...

final yttrium = ExternalLibrary.open('....');
await frb.YttriumDart.init(externalLibrary: yttrium);

[fzyzcjy]

Usually a single line is enough (which is the default way and I have not heard people saying this causes the app store issue before):

await frb.YttriumDart.init();

Could you please try whether that works for you?

[quetool]

So, I created a brand new package (plugin) following QuickStart guide and after setting everything up and running the app I ended up having the same issue:

Invalid argument(s): Failed to load dynamic library 'yttrium.framework/yttrium': dlopen(yttrium.framework/yttrium, 0x0001): tried: 'yttrium.framework/yttrium' (no such file), '/private/preboot/Cryptexes/OSyttrium.framework/yttrium' (no such file), '/private/var/containers/Bundle/Application/678D9715-BC78-4A30-BF55-A49037118DAB/Runner.app/yttrium.framework/yttrium' (no such file), '/private/var/containers/Bundle/Application/678D9715-BC78-4A30-BF55-A49037118DAB/Runner.app/Frameworks/yttrium.framework/yttrium' (no such file), '/private/var/containers/Bundle/Application/678D9715-BC78-4A30-BF55-A49037118DAB/Runner.app/Frameworks/yttrium.framework/yttrium' (no such file), '/usr/lib/yttrium.framework/yttrium' (no such file, not in dyld cache), 'yttrium.framework/yttrium' (no such file)

---

I'll try to paint the whole picture cause I think I'm in a dead-end with my knowledge:

We have this repo called yttrium which is the workspace for our crates...

Inside yttrium we have /crates and one of them is reown_yttrium and another one is yttrium, which is the crate with the rust code.

Now, reown_yttrium is just a flutter package generated with flutter_rust_bridge_codegen create reown_yttrium --template plugin from which I deleted the /rust folder and Cargo files. Why? Because I'm generating code from ../yttrium, which is the crate with the rust code

The sis flutter_rust_bridge.yaml:

rust_root: "../yttrium/" # rust code entry point relative to local path
rust_input: crate::chain_abstraction::dart_compat #,alloy,ruint,alloy-primitives
dart_output: lib/generated/ # output path for generated Dart code
# c_output: bridge_generated.h
# duplicated_c_output: args.duplicated_c_output,
# full_dep: true
web: false
# local: true
# stop_on_error: true
build_runner: true
dart_entrypoint_class_name: "ReownYttrium"
dart_format_line_length: 80
# dart_preamble: args.dart_preamble,
# rust_preamble: args.rust_preamble,
# dart_enums_style: negative_bool_arg(args.no_dart_enums_style),
add_mod_to_lib: true
# llvm_path: args.llvm_path,
# llvm_compiler_opts: args.llvm_compiler_opts,
# dart_root: args.dart_root,
# extra_headers: args.extra_headers,
deps_check: true
dart3: true
# default_external_library_loader_web_prefix: args.default_external_library_loader_web_prefix,
# dart_type_rename: None, // complex type, not supported on command line yet
enable_lifetime: true
# type_64bit_int: positive_bool_arg(args.type_64bit_int),
# default_dart_async: negative_bool_arg(args.no_default_dart_async),
# dump: args.dump,
# dump_all: true
rust_features: [frb]

After changing the podspec file for the package...

#
# To learn more about a Podspec see http://guides.cocoapods.org/syntax/podspec.html.
# Run `pod lib lint reown_yttrium.podspec` to validate before publishing.
#
Pod::Spec.new do |s|
  s.name             = 'reown_yttrium'
  s.version          = '0.0.1'
  s.summary          = 'A new Flutter FFI plugin project.'
  s.description      = <<-DESC
A new Flutter FFI plugin project.
                       DESC
  s.homepage         = 'http://example.com'
  s.license          = { :file => '../LICENSE' }
  s.author           = { 'Your Company' => 'email@example.com' }

  # This will ensure the source files in Classes/ are included in the native
  # builds of apps using this FFI plugin. Podspec does not support relative
  # paths, so Classes contains a forwarder C file that relatively imports
  # `../src/*` so that the C sources can be shared among all target platforms.
  s.source           = { :path => '.' }
  s.source_files = 'Classes/**/*'
  s.dependency 'Flutter'
  s.platform = :ios, '11.0'

  # Flutter.framework does not contain a i386 slice.
  s.pod_target_xcconfig = { 'DEFINES_MODULE' => 'YES', 'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386' }
  s.swift_version = '5.0'

  s.script_phase = {
    :name => 'Build Rust library',
    # First argument is relative path to the `rust` folder, second is name of rust library
    :script => 'sh "$PODS_TARGET_SRCROOT/../cargokit/build_pod.sh" ../../yttrium yttrium',
    :execution_position => :before_compile,
    :input_files => ['${BUILT_PRODUCTS_DIR}/cargokit_phony'],
    # Let XCode know that the static library referenced in -force_load below is
    # created by this build step.
    :output_files => ["${BUILT_PRODUCTS_DIR}/libyttrium.a"],
  }
  s.pod_target_xcconfig = {
    'DEFINES_MODULE' => 'YES',
    # Flutter.framework does not contain a i386 slice.
    'EXCLUDED_ARCHS[sdk=iphonesimulator*]' => 'i386',
    'OTHER_LDFLAGS' => '-force_load ${BUILT_PRODUCTS_DIR}/libyttrium.a',
  }
end

I was able to run the example app but it fails to load the framework/library with the error above...

cargokit seems to be "working" (at least its not erroring) and I see the framework inside the build folder, everything seems to be bundling properly but still failing to load it

And I'm using just await frb.ReownYttrium.init(); to load it...

So I really don't know what could be happening, I'm already squeezed my brain out along with ChatGPT and Grok to sort this out but nothing... :(

[quetool]

If I hardcode one of the paths showed in the error like this:

final yttrium = ExternalLibrary.open(
'/private/var/containers/Bundle/Application/ED00EAE4-BEAC-403B-9C3E-DAC244332C72/Runner.app/Frameworks/reown_yttrium.framework/reown_yttrium',
);
        // Initialize the Rust library
await frb.ReownYttrium.init(externalLibrary: yttrium);

then I see this error...

[ +223 ms] flutter: Invalid argument(s): Invalid argument(s): Failed to lookup symbol 'frb_get_rust_content_hash': dlsym(0x4208ec60, frb_get_rust_content_hash): symbol not found
[        ] flutter: This is often because the Rust library is not loaded correctly.
[        ] flutter: Debug information of the external library: by open(/private/var/containers/Bundle/Application/ED00EAE4-BEAC-403B-9C3E-DAC244332C72/Runner.app/Frameworks/reown_yttrium.framework/reown_yttrium)
[        ] flutter: Original stack trace: #0      DynamicLibrary.lookup (dart:ffi-patch/ffi_dynamic_library_patch.dart:33:70)
[        ] flutter: #1      MultiPackageCBinding._frb_get_rust_content_hashPtr (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart:327:56)
[        ] flutter: #2      MultiPackageCBinding._frb_get_rust_content_hashPtr (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart)
[        ] flutter: #3      MultiPackageCBinding._frb_get_rust_content_hash (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart:330:7)
[        ] flutter: #4      MultiPackageCBinding._frb_get_rust_content_hash (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart)
[        ] flutter: #5      MultiPackageCBinding.frb_get_rust_content_hash (package:flutter_rust_bridge/src/ffigen_generated/multi_package.dart:323:12)
[        ] flutter: #6      GeneralizedFrbRustBinding.getRustContentHash (package:flutter_rust_bridge/src/generalized_frb_rust_binding/_io.dart:69:23)
[        ] flutter: #7      BaseEntrypoint._sanityCheckContentHash (package:flutter_rust_bridge/src/main_components/entrypoint.dart:106:35)
[        ] flutter: #8      BaseEntrypoint.initImpl (package:flutter_rust_bridge/src/main_components/entrypoint.dart:52:5)
[        ] flutter: #9      ReownYttrium.init (package:reown_yttrium/generated/frb_generated.dart:31:20)
[        ] flutter: #10     YttriumClient.init (package:reown_yttrium/yttrium_dart_client.dart:40:32)
[        ] flutter: #11     _HomePageState._initialize (package:reown_yttrium_example/main.dart:85:36)
[        ] flutter: #12     _HomePageState.initState (package:reown_yttrium_example/main.dart:79:5)
[        ] flutter: #13     StatefulElement._firstBuild (package:flutter/src/widgets/framework.dart:5748:55)
[        ] flutter: #14     ComponentElement.mount (package:flutter/src/widgets/framework.dart:5593:5)
...

[fzyzcjy]

So, I created a brand new package (plugin) following QuickStart guide and after setting everything up and running the app I ended up having the same issue:

That's really weird... The quickstart is ensured in CI that everything works well, and seems other people are using it without errors.

Just to double check: Do you mean this command -

[quetool]

Yes, that's the one. And the default package that is generated after that command works just fine but I tweaked to suite my needs and it stopped working with the error.

I now think this is the proper way of loading the framework:

final yttrium = ExternalLibrary.open('reown_yttrium.framework/reown_yttrium');
await frb.RustLib.init(externalLibrary: yttrium);

but this leads me to the symbol not found error:

[ +351 ms] flutter: Invalid argument(s): Invalid argument(s): Failed to lookup symbol 'frb_get_rust_content_hash': dlsym(0x4208ec60, frb_get_rust_content_hash): symbol not found
[        ] flutter: This is often because the Rust library is not loaded correctly.
[        ] flutter: Debug information of the external library: by open(reown_yttrium.framework/reown_yttrium)
[        ] flutter: Original stack trace: #0      DynamicLibrary.lookup (dart:ffi-patch/ffi_dynamic_library_patch.dart:33:70)

Why do I think this is the proper way to load it? Because with any other way it throws me the Failed to load dynamic library (not found) error and also I have checked for the frb_get_rust_content_hash symbol in the package generated by default and indeed it's there:

Mac:package_demo alfreedom$ nm -gU example/build/ios/Debug-iphoneos/package_demo/package_demo.framework/package_demo | grep frb_get_rust_content_hash
000000000000b840 T _frb_get_rust_content_hash
Mac:my_package_demo alfreedom$ 

But when I try on the affected package is output is not produced...
I'm not really expert on rust but I'm assuming these symbols are getting stripped somehow