Question

请理解我无法在此处上传整个代码。

我有

@interface BcsProcessor : NSObject <AVCaptureMetadataOutputObjectsDelegate> {}

和BcsProcessor有setupCaptureSession和captureOutput方法。

- (void)captureOutput:(AVCaptureOutput*)captureOutput didOutputMetadataObjects:(NSArray*)metadataObjects fromConnection:(AVCaptureConnection*)connection


- (NSString*)setUpCaptureSession {
    NSError* error = nil;

    AVCaptureSession* captureSession = [[[AVCaptureSession alloc] init] autorelease];
    self.captureSession = captureSession;

       AVCaptureDevice* __block device = nil;
    if (self.isFrontCamera) {

        NSArray* devices = [AVCaptureDevice devicesWithMediaType:AVMediaTypeVideo];
        [devices enumerateObjectsUsingBlock:^(AVCaptureDevice *obj, NSUInteger idx, BOOL *stop) {
            if (obj.position == AVCaptureDevicePositionFront) {
                device = obj;
            }
        }];
    } else {
        device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
    }

    AVCaptureDeviceInput* input = [AVCaptureDeviceInput deviceInputWithDevice:device error:&error];

    AVCaptureMetadataOutput* output = [[[AVCaptureMetadataOutput alloc] init] autorelease];
    output.metadataObjectTypes = output.availableMetadataObjectTypes

    dispatch_queue_t outputQueue = dispatch_queue_create("com.1337labz.featurebuild.metadata", 0);
    [output setMetadataObjectsDelegate:self queue:outputQueue];

    captureSession.sessionPreset = AVCaptureSessionPresetPhoto;

    if ([captureSession canAddInput:input]) {
        [captureSession addInput:input];
    }

    if ([captureSession canAddOutput:output]) {
        [captureSession addOutput:output];
    }

    // setup capture preview layer
    self.previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:captureSession];

    // run on next event loop pass [captureSession startRunning]
    [captureSession performSelector:@selector(startRunning) withObject:nil afterDelay:0];

    return nil;
}

因此，上面的代码会设置会话并添加AVCaptureMetadataOutput。并且BcsProcessor应该接收捕获的元数据。但是我的captureOutput方法没有收到任何数据，也没有被调用。

我会感谢任何帮助或评论。

Answer 1

首先确保您的输入和输出正确添加到会话中。您可以登录captureSession.inputs和captureSession.outputs进行检查。

第二，确保正确设置output.metadataObjectTypes意味着availableMetadataObjectTypes的输出不为空。如果在添加输出之前调用它，我相信这将是空的。

最后我没有看到您将预览图层添加到视图图层在使用会话初始化图层后尝试...

self.previewLayer.frame = self.view.layer.bounds;
[self.view.layer addSublayer:previewLayer];

iOS7 AVCapture captureOutput永远不会被调用

1 个答案: