ios - iOS 中的条码扫描器

Question

我使用 AV Foundation 框架实现条码扫描功能。

session = [[AVCaptureSession alloc] init];
device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
NSError *error = nil;

input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];
if (input) {
    [session addInput:input];
} else {
    NSLog(@"Error: %@", error);
}

output = [[AVCaptureMetadataOutput alloc] init];
[output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];
[session addOutput:output];

output.metadataObjectTypes = [output availableMetadataObjectTypes];

prevLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
prevLayer.frame = self.view.bounds;

使用 delegete 方法我将得到条形码结果。即条形码编号

- (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputMetadataObjects:(NSArray *)metadataObjects fromConnection:(AVCaptureConnection *)connection
{
    CGRect highlightViewRect = CGRectZero;
    AVMetadataMachineReadableCodeObject *barCodeObject;
    NSString *detectionString = nil;
    NSArray *barCodeTypes = @[AVMetadataObjectTypeUPCECode, AVMetadataObjectTypeCode39Code, AVMetadataObjectTypeCode39Mod43Code,
            AVMetadataObjectTypeEAN13Code, AVMetadataObjectTypeEAN8Code, AVMetadataObjectTypeCode93Code, AVMetadataObjectTypeCode128Code,
            AVMetadataObjectTypePDF417Code, AVMetadataObjectTypeQRCode, AVMetadataObjectTypeAztecCode];

    for (AVMetadataObject *metadata in metadataObjects) {
        for (NSString *type in barCodeTypes) {
            if ([metadata.type isEqualToString:type])
            {
                barCodeObject = (AVMetadataMachineReadableCodeObject *)[_prevLayer transformedMetadataObjectForMetadataObject:(AVMetadataMachineReadableCodeObject *)metadata];
                barcodeString = [(AVMetadataMachineReadableCodeObject *)metadata stringValue];
                break;
            }
        }

        if (barcodeString != nil)
        {
            NSLog(@"Barcode String: %@",barcodeString);
        }
        else
            label.text = @"(none)";
    }
}

注意:它的工作。但是，主要原因是，我总是无法获得条形码编号。你能帮我解决这个问题吗？

Answer 1

您的委托(delegate)方法看起来不错，但您应该添加:videoGravity 到您的 AVCaptureVideoPreviewLayer (prevLayer) 并启动 session 。尝试在第一个方法的末尾添加这些代码行:

prevLayer.videoGravity = AVLayerVideoGravityResizeAspectFill;
[self.view.layer addSublayer:prevLayer];  
[session startRunning];