CODEWITHSUNDEEP
objective-cavfoundation
JIANG
JIANG

Reputation: 1877

AVCaptureMetadataOutput unsupported type found error in XCode

Error Log: Terminating app due to uncaught exception 'NSInvalidArgumentException', reason: '* -[AVCaptureMetadataOutput setMetadataObjectTypes:] - unsupported type found. Use -availableMetadataObjectTypes.' * First throw call stack:

This is the availableMetadataObjectTypes in debugger log. I don't understand why this is empty.

(lldb) po [output availableMetadataObjectTypes] <__NSArrayM 0x810ae990>()

Here is the code NSError* error;

session = [[AVCaptureSession alloc] init];
[session setSessionPreset:AVCaptureSessionPresetHigh];

AVCaptureDevice* device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

AVCaptureDeviceInput* deviceInput = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if ([session canAddInput:deviceInput]) {
    [session addInput:deviceInput];
}

previewLayer = [[AVCaptureVideoPreviewLayer alloc] initWithSession:session];
[previewLayer setVideoGravity:AVLayerVideoGravityResizeAspectFill];

CALayer *rootLayer = [[self scannerView] layer];
[rootLayer setMasksToBounds:YES];
[previewLayer setFrame:CGRectMake(self.scannerView.frame.origin.x, self.scannerView.frame.origin.y, self.scannerView.frame.size.width, self.scannerView.frame.size.height)];
[rootLayer insertSublayer:previewLayer atIndex:0];

_labelBarcode = [[UILabel alloc] initWithFrame:CGRectMake(0, 20, 300, 40)];
_labelBarcode.backgroundColor = [UIColor darkGrayColor];
_labelBarcode.textColor = [UIColor whiteColor];
[self.scannerView addSubview:_labelBarcode];

[self rotatePreviewLayerToDeviceOrientation];

[session startRunning];

AVCaptureMetadataOutput* output = [[AVCaptureMetadataOutput alloc] init];
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
if ([session canAddOutput:output]) {
    [session addOutput:output];
}
[output availableMetadataObjectTypes];
output.metadataObjectTypes = @[
                               AVMetadataObjectTypeAztecCode,
                               AVMetadataObjectTypeCode128Code,
                               AVMetadataObjectTypeCode39Code,
                               AVMetadataObjectTypeCode39Mod43Code,
                               AVMetadataObjectTypeCode93Code,
                               AVMetadataObjectTypeEAN13Code,
                               AVMetadataObjectTypeEAN8Code
                               ];

}

Upvotes: 0

Views: 2100

Answers (1)

Gordon Childs
Gordon Childs

Reputation: 36074

You should check availableMetadataObjectTypes, but if you haven't added an input device, the list will be empty.

The hint comes from a comment on availableMetadataObjectTypes in AVCaptureOutput.h:

Available metadata object types are dependent on the capabilities of the AVCaptureInputPort to which this receiver's AVCaptureConnection is connected.

e.g. my back camera supports aztec and code128.

NSError *error;
AVCaptureSession *session = [[AVCaptureSession alloc] init];
AVCaptureDevice *captureDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
AVCaptureDeviceInput *input = [AVCaptureDeviceInput deviceInputWithDevice:captureDevice error:&error];

// Check input and error here.

[session addInput:input];


AVCaptureMetadataOutput* output = [[AVCaptureMetadataOutput alloc] init];
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
if ([session canAddOutput:output]) {
    [session addOutput:output];
}

// NOW try adding metadata types
session.metadataObjectTypes = @[AVMetadataObjectTypeAztecCode,
                           AVMetadataObjectTypeCode128Code];

Upvotes: 7

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