iOS7之后扫一扫使用AVCapture出现 unsupported type found. Use -availableMetadataObjectTypes错误的解决

- (void)setupCamera

{

    // Device

    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    

    // Input

    _input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];

    

    // Output

    if (!_output) {

        _output = [[AVCaptureMetadataOutput alloc] init];

    }

    

    [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

    

    // Session

    if (!_session) {

        _session = [[AVCaptureSession alloc] init];

    }

    

    [_session setSessionPreset:AVCaptureSessionPresetHigh];

    if ([_session canAddInput:self.input])

    {

        [_session addInput:self.input];

    }

    

    if ([_session canAddOutput:self.output])

    {

        [_session addOutput:self.output];

    }

    

    // 条码类型 AVMetadataObjectTypeQRCode

    _output.metadataObjectTypes =@[AVMetadataObjectTypeQRCode];

 

    // Preview

    _preview =[AVCaptureVideoPreviewLayer layerWithSession:self.session];

    _preview.videoGravity = AVLayerVideoGravityResizeAspectFill;

    _preview.frame =CGRectMake(0,0,mScreenWidth,mScreenHeight);

    [self.view.layer insertSublayer:self.preview atIndex:0];

    

    // Start

    [_session startRunning];

    

    timer = [NSTimer scheduledTimerWithTimeInterval:.02 target:self selector:@selector(animation1) userInfo:nil repeats:YES];

}

修改之后

- (void)setupCamera

{

    // Device

    _device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

    

    // Input

    _input = [AVCaptureDeviceInput deviceInputWithDevice:self.device error:nil];

    

    // Output

    if (!_output) {

        _output = [[AVCaptureMetadataOutput alloc] init];

    }

    

    [_output setMetadataObjectsDelegate:self queue:dispatch_get_main_queue()];

    

    // Session

    if (!_session) {

        _session = [[AVCaptureSession alloc] init];

    }

    

    [_session setSessionPreset:AVCaptureSessionPresetHigh];

    if ([_session canAddInput:self.input])

    {

        [_session addInput:self.input];

    }

    

    if ([_session canAddOutput:self.output])

    {

        [_session addOutput:self.output];

    }

    

    // 条码类型 AVMetadataObjectTypeQRCode

    _output.metadataObjectTypes = [NSArray arrayWithObject:AVMetadataObjectTypeQRCode];

 

    // Preview

    _preview =[AVCaptureVideoPreviewLayer layerWithSession:self.session];

    _preview.videoGravity = AVLayerVideoGravityResizeAspectFill;

    _preview.frame =CGRectMake(0,0,mScreenWidth,mScreenHeight);

    [self.view.layer insertSublayer:self.preview atIndex:0];

    

    // Start

    [_session startRunning];

    

    timer = [NSTimer scheduledTimerWithTimeInterval:.02 target:self selector:@selector(animation1) userInfo:nil repeats:YES];

}

AVCaptureMetadataOutput类的对象(在本例里是self.outPut),self.outPut的属性metadataObjectTypes要在AVCaptureSession类对象（本例为self.session)

[self.session addOutput:self.outPut]即添加了AVCaptureMetadataOutput的对象后，方可对其进行设置；