What would be the condition in a while loop using the FaceRecognizer - xcode

Question

How do I make an while loop with FaceRecognizer so that while a face is recognized, a command will happen? I am not sure what the condition would be. What variable do I use and what to I equate it to?
Here is my code
#import "ViewController.h"
NSString* const faceCascadeFilename = #"haarcascade_frontalface_alt2";
const int HaarOptions = CV_HAAR_FIND_BIGGEST_OBJECT | CV_HAAR_DO_ROUGH_SEARCH;
#interface ViewController ()
#end
#implementation ViewController
#synthesize videoCamera;
- (void)viewDidLoad
{
[super viewDidLoad];
// Do any additional setup after loading the view, typically from a nib.
self.videoCamera = [[CvVideoCamera alloc] initWithParentView:imageView];
self.videoCamera.defaultAVCaptureDevicePosition = AVCaptureDevicePositionFront;
self.videoCamera.defaultAVCaptureSessionPreset = AVCaptureSessionPreset352x288;
self.videoCamera.defaultAVCaptureVideoOrientation = AVCaptureVideoOrientationPortrait;
self.videoCamera.defaultFPS = 30;
self.videoCamera.grayscaleMode = NO;
self.videoCamera.delegate = self;
NSString* faceCascadePath = [[NSBundle mainBundle] pathForResource:faceCascadeFilename ofType:#"xml"];
faceCascade.load([faceCascadePath UTF8String]);
Label1.hidden=YES;
}
- (void)didReceiveMemoryWarning
{
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
#pragma mark - Protocol CvVideoCameraDelegate
#ifdef __cplusplus
- (void)processImage:(Mat&)image;
{
Mat grayscaleFrame;
cvtColor(image, grayscaleFrame, CV_BGR2GRAY);
equalizeHist(grayscaleFrame, grayscaleFrame);
std::vector<cv::Rect> faces;
faceCascade.detectMultiScale(grayscaleFrame, faces, 1.1, 2, HaarOptions, cv::Size(60, 60));
for (int i = 0; i < faces.size(); i++)
{
cv::Point pt1(faces[i].x + faces[i].width, faces[i].y + faces[i].height);
cv::Point pt2(faces[i].x, faces[i].y);
cv::rectangle(image, pt1, pt2, cvScalar(0, 255, 0, 0), 1, 8 ,0);
}
}
//#endif
#pragma mark - UI Actions
- (IBAction)startCamera:(id)sender
{
[self.videoCamera start];
imageView.hidden=YES;
while (FaceRecognizer...) {
Label1.hidden=NO;
}
}