//1.创建捕捉会话

AVCaptureSession *session = [[AVCaptureSession alloc] init];

//2.添加一个输入源

AVCaptureDevice *device = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];

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

[session addInput:input];

self.session = session;

//3.添加一个输出源

AVCaptureMetadataOutput *output = [[AVCaptureMetadataOutput alloc] init];

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

[session addOutput:output];

[output setMetadataObjectTypes:@[AVMetadataObjectTypeQRCode]];

//4.添加一个预览图层

AVCaptureVideoPreviewLayer *layer = [AVCaptureVideoPreviewLayer layerWithSession:session];

layer.frame = self.view.bounds;

[self.view.layer addSublayer:layer];

self.layer = layer;

// 5.开启扫描

[session startRunning];

#pragma mark - 实现输出源的代理方法

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

{

    if (metadataObjects.count > ) {

        AVMetadataMachineReadableCodeObject *object = [metadataObjects lastObject];

        NSLog(@"%@", object.stringValue);

        [self.session stopRunning];

        [self.layer removeFromSuperlayer];

    } else {

        NSLog(@"获取数据失败");

    }

}