Only Last frame of a video displayed in Xcode Simulator - objective-c

Question

I'm applying some signal-processing techniques to a video by extracting a frame from the video and displaying the result to the image view before extracting the next frame. In my program, inside the -(void)viewDidload{}, I have a while loop that loops through 30 images and displays each one to the view. The problem I am having is that the image view ( UIImageView) never shows the image at each loop and only displays the last image. I want the new image to be shown every time a new frame is extracted.
I checked that the code is looping through all the images extracted from the video by pure outing frame count inside the while loop, but the imageview shows nothing.
Here is the problem code:
#interface ViewController () {
UIImageView *imageView_;
}
#end
#implementation ViewController
- (void)viewDidLoad {
[super viewDidLoad];
imageView_ = [[UIImageView alloc]initWithFrame:CGRectMake(100, 100, 190, 190)];
imageView_.contentMode = UIViewContentModeScaleAspectFill;
string data = "eyesample.mp4";
cv::VideoCapture original_video_data;
original_video_data.open(data);
int count = 0;
int total;
int nFrames;
cv::Mat frame;
frame = NULL;
total = original_video_data.get(cv::CAP_PROP_FRAME_COUNT);
cout <<"the total number of frames are :" << total << endl;
while (count < 30)
{
original_video_data >> frame ;
if (frame.empty()) {
break;
}
nFrames = original_video_data.get(cv::CAP_PROP_POS_FRAMES); // frame elemnt counter
cout << "Frame: " << nFrames << endl;
cout << count++ << endl;
imageView_.image = MatToUIImage(frame);
[self.view addSubview:imageView_];
}
original_video_data.release();
}