Google MLKIt TextRecognition on iOS return always empty result

Question

I am using react-native, react-native-vision-camera (with frameProcessor) and mlkit to perform in device text recognition.

My code works on Android, but I got always empty results on iOS.

Here is my Objective C implementation:

static inline id scanOCR(Frame* frame, NSArray* args) {
  MLKTextRecognizer *textRecognizer = [MLKTextRecognizer textRecognizer];
  MLKVisionImage *image = [[MLKVisionImage alloc] initWithBuffer:frame.buffer];
  image.orientation = frame.orientation;
  
  NSError *error;
  MLKText *result = [textRecognizer resultsInImage:image error:&error];
  if (error != nil || result == nil) {
    NSLog(@"%@", error); // <- This is NEVER called
  } else {
    NSLog(@"text: %@", result.text); // <- this is always empty
    NSLog(@"blocks lenght: %lu", (unsigned long)result.blocks.count); // <- this is always 0
  }
  return @{@"text": result.text};  
}

The project corretly compile, with no errors, but results.text is always empty, even if the camera is framing texts.

I think that MLKit is corretly installed. This is my Podfile

require_relative '../node_modules/react-native/scripts/react_native_pods'
require_relative '../node_modules/@react-native-community/cli-platform-ios/native_modules'

platform :ios, '11.0'

target 'com.digitalbore.papertag' do
  config = use_native_modules!

  use_react_native!(
    :path => config[:reactNativePath],
    # to enable hermes on iOS, change `false` to `true` and then install pods
    :hermes_enabled => false
  )

  pod 'GoogleMLKit/TextRecognition','2.2.0'

  target 'com.digitalbore.papertagTests' do
    inherit! :complete
    # Pods for testing
    pod 'react-native-splash-screen', :path => '../node_modules/react-native-splash-screen'

    pod 'react-native-receive-sharing-intent', :path => '../node_modules/react-native-receive-sharing-intent'

  end

  # Enables Flipper.
  #
  # Note that if you have use_frameworks! enabled, Flipper will not work and
  # you should disable the next line.
  use_flipper!()

  post_install do |installer|
    react_native_post_install(installer)
    __apply_Xcode_12_5_M1_post_install_workaround(installer)
  end
end

Answer 1

To further understand the situation here, could you verify that you are not getting any text result with the Google ML Kit quickstart vision app on your device?