Crash metadataOutput AVCaptureMetadata

[seth35us]

Looks like this crash is back in version 1.1.2 on iOS, assuming the most recent build too, since I didn't see any code changes in the file that is crashing. The firebase error is: $s20fast_barcode_scanner13BarcodeReaderC14metadataOutput_03didG04fromySo017AVCaptureMetadataG0C_SaySo16AVMetadataObjectCGSo0J10ConnectionCtFTf4dndn_n + 724. I am waiting for xcode to give me more information.

I think this is related to #17. However, the error did not occur in the fixes from #17. This is the file that the crash is occurring in: https://github.com/jhoogstraat/fast_barcode_scanner/blob/main/fast_barcode_scanner/ios/Classes/BarcodeReader.swift

I am still waiting for Xcode to tell me where the crash is. Have you been seeing the same crash? I am thinking I could just add a few guards on that file and try it?

[jhoogstraat]

Do you know more parameters to the crash? Like which devices are affected or which version of iOS?

Demangled symbol:

function signature specialization of fast_barcode_scanner.BarcodeReader.metadataOutput(_: __C.AVCaptureMetadataOutput, didOutput: Swift.Array<__C.AVMetadataObject>, from: __C.AVCaptureConnection) -> ()

Which is

func metadataOutput(_ output: AVCaptureMetadataOutput,
                        didOutput metadataObjects: [AVMetadataObject],
                        from connection: AVCaptureConnection) {
        guard
            let metadata = metadataObjects.first,
            let readableCode = metadata as? AVMetadataMachineReadableCodeObject
            else { return }

        pauseIfRequired()

        codeCallback([flutterMetadataObjectTypes[readableCode.type]!, readableCode.stringValue!])
    }

The only possible cause could be the force unwrappings here: [flutterMetadataObjectTypes[readableCode.type]!, readableCode.stringValue!].

The first one is really unlikely to have caused the crash, because AVFoundation supports a fixed range of code types which I just copied into flutterMetadataObjectTypes.

Are there code types that do not have a value?

Anyway I guess it would be good to have both unwrappings in the guard statement as it is in #17.

[seth35us]

I do not know what code types do not have a value. I think you are correct. I have modified the code in my project below and will see if the crash goes away. Do you want me to do a PR, or do you want to make the change?

Thank you for looking into this error.

func metadataOutput(_ output: AVCaptureMetadataOutput,
                        didOutput metadataObjects: [AVMetadataObject],
                        from connection: AVCaptureConnection) {
        guard
            let metadata = metadataObjects.first,
            let readableCode = metadata as? AVMetadataMachineReadableCodeObject,

            let type = flutterMetadataObjectTypes[readableCode.type],
                    let value = readableCode.stringValue

            else { return }

        pauseIfRequired()

        codeCallback([type, value])
    }

[jhoogstraat]

Did we fix this issue in the develop branch? Not sure where we left of.

[seth35us]

I did not edit development. I ended up trying this package instead: https://pub.dev/packages/fl_mlkit_scanning. It seems really good, but possibly cpu intensive. I may try your cpu tests to see how it compares to AVFoundation.

[jhoogstraat]

Too bad. The force unwrapping is gone on develop branch, so the bug should not happen on there, if you like to try again!

[seth35us]

Thanks, I will try again. I appreciate you fixing the issues!