IOS8: custom keyboard - open camera with AVCaptureVideoPreviewLayer on keyboard background

Is it possible to open AVCaptureVideoPreviewLayer in front of an iOS8 custom keyboard? I tried with this code

    AVCaptureSession *session = [[AVCaptureSession alloc] init];
AVCaptureDevice *videoDevice = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeVideo];
if (videoDevice)
{
    NSError *error;
    AVCaptureDeviceInput *videoInput = [AVCaptureDeviceInput deviceInputWithDevice:videoDevice error:&error];
    if (!error)
    {
        if ([session canAddInput:videoInput])
        {
            [session addInput:videoInput];
            AVCaptureVideoPreviewLayer *previewLayer = [AVCaptureVideoPreviewLayer layerWithSession:session];
            previewLayer.frame = self.bounds;
            NSLog(@"open %@",NSStringFromCGRect(self.bounds));
            [self.camView.layer addSublayer:previewLayer];
            [session startRunning];
        }
    }
}

      

        
        
        
      

    

It asks for permission to use the camera, but not open the camera in the background of the keyboard. Please help me. Thank.