IOS emulator not work

[maxmeng93]

I used the official demo provided, but it does not work on the iOS simulator, it shows a black screen.

import 'package:mobile_scanner/mobile_scanner.dart';

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Mobile Scanner')),
      body: MobileScanner(
        // fit: BoxFit.contain,
        onDetect: (capture) {
          final List<Barcode> barcodes = capture.barcodes;
          final Uint8List? image = capture.image;
          for (final barcode in barcodes) {
            debugPrint('Barcode found! ${barcode.rawValue}');
          }
        },
      ),
    );
  }

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[✓] Connected device (4 available)
    • xxxxxxxiPhone (mobile)        • 00008110-000E602C3E44401E            • ios            • iOS 17.4.1 21E236
    • iPhone 15 Pro Max (mobile) • 5A15D2C8-08DE-4033-891C-CC7E3800782A • ios            • com.apple.CoreSimulator.SimRuntime.iOS-17-0 (simulator)
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• No issues found!
Process finished with exit code 0

[navaronbracke]

You have to test using a real device, this is working as intended.

The iOS Simulator does not provide a "real" camera to provide images with, so mobile_scanner would never work on it.

The Android Emulator does provide a "fake" camera view, but unless that fake view provides an image with a barcode, you can't test using that either.

[maxmeng93]

@navaronbracke I tested the example barcode_scanner_controller.dart in mobile_scanner@5.0.0-beta.3 on my iPhone. When I first entered the page, it showed a black screen without rendering the camera view on the page, but it could scan correctly. However, when I clicked the start button at this time, the page would throw an error.

https://github.com/juliansteenbakker/mobile_scanner/assets/16930628/85c7c65b-5a26-4777-8a4f-18b196333a5c

[maxmeng93]

When I commented out unawaited(controller.start()); in initState(), and then clicked the start button, everything became normal.

[navaronbracke]

That seems to be an oversight in the sample indeed. Since we have a manual "start" button, starting the controller in initState() defeats the purpose of said sample. I wonder why it only causes an issue on iOS, though? (I have been using that exact sample to test things out on Android / MacOS and web; but I didn't have an iOS device to test things on for a while)

I'll fix up the sample and test with an iOS device.