How to use camera as backgroud view in iPhone app

This action starts camera as a backgroud of the view:-

-(IBAction)btnStartCamera_TouchUpInside{

picker = [[UIImagePickerController alloc] init];

#if TARGET_IPHONE_SIMULATOR

picker.sourceType = UIImagePickerControllerSourceTypePhotoLibrary;

picker.view = viewCategoryCamera;

#elif TARGET_OS_IPHONE

picker.sourceType = UIImagePickerControllerSourceTypeCamera;

picker.showsCameraControls = NO;

[picker.view addSubview:viewCategoryCamera];

//picker.cameraOverlayView = viewCamera;

#endif

[self presentModalViewController:picker animated:YES];

}

This action stops camera:-

-(IBAction)btnStopCamera_TouchUpInside:(id)sender{

[self dismissModalViewControllerAnimated:YES];

[self.navigationController popToRootViewControllerAnimated:YES];

}