Importing a static library (Rust .a) to Flutter project in iOS - ios

Question

I have followed the instructions from here and here
And although the .a library and the functions work as expected on Debug (simulator and real device), when I Archive and test through TestFlight the Flutter App begins with a grey background (which I read that it means some kind of error).
If I go ahead and remove all calls of the Rust lib then the Testflight opens normally.
Note: I have also added the .a library as a Linked framework from the XCode and I have included the .h file to the bridging-header.h of the project.
I have also
run flutter build --release
cleared the derived data
pods cache
even re-made the iOS folder
from scratch.
Is there something else that I'm missing here?

Answer 1

I managed to make it work by creating a Flutter plugin flutter create -t plugin then I imported the .a file on the /iOS folder and included all the rust functions on the .h file inside /iOS/Classes (these are automatically created).
Then add a sample function for each of the rust functions inside the .Swift file in /iOS/Classes
And make sure to include
flutter:
plugin:
pluginClass: ApproverRustPlugin
On your .yaml file of the plugin.
Also include these on the plugin .podspec file
s.public_header_files = 'Classes**/*.h'
s.source_files = 'Classes/**/*'
s.static_framework = true
s.vendored_libraries = "**/*.a"
Once all these are done. Make sure to include your plugin (assuming it exists on the same folder as the main App) on the main app .yaml file.
dependencies:
flutter:
sdk: flutter
approver_rust:
path: "./approver_rust"
For reference:
Pod::Spec.new do |s|
s.name = 'approver_rust'
s.version = '0.0.1'
s.summary = 'A new flutter plugin project.'
s.description = <<-DESC
A new flutter plugin project.
DESC
s.homepage = 'http://example.com'
s.license = { :file => '../LICENSE' }
s.author = { 'Your Company' => 'email#example.com' }
s.source = { :path => '.' }
s.public_header_files = 'Classes**/*.h'
s.source_files = 'Classes/**/*'
s.static_framework = true
s.vendored_libraries = "**/*.a"
s.dependency 'Flutter'
s.platform = :ios, '9.0'
# 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'
end