无法用叠加拍照

Question

我正在使用UIImagePickercontroller拍照。我在UIScrollview下有图片。当我从scrollview点击特定图像时，图像将是imageView的子视图。并且imageView将出现在overlayView的叠加层上。当我从上到下或在cameraView上的任何地方移动特定图像时，我需要拍摄叠加照片。但是我无法用叠加来拍摄照片。

代码：

picker = [[UIImagePickerController alloc] init];


    // Set the image picker source:
    // picker.sourceType = UIImagePickerControllerSourceTypeCamera;

    // Hide the controls:
    picker.showsCameraControls = YES;
    picker.navigationBarHidden = YES;

    picker.delegate=self;

    // Make camera view full screen:
    picker.wantsFullScreenLayout = YES;

    // Insert the overlay:
     picker.cameraOverlayView = self.view;



    self.view.backgroundColor=[UIColor clearColor];

    // Show the picker:
     [self presentModalViewController:picker animated:YES];

-(void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
    UIImageWriteToSavedPhotosAlbum(image,self,
                                   @selector(image:finishedSavingWithError:contextInfo:),
                                   nil);
}

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo
{
    UIAlertView *alert;


    if (error)
        alert = [[UIAlertView alloc] initWithTitle:@"Error"
                                           message:@"Unable to save image to Photo Album."
                                          delegate:self cancelButtonTitle:@"Ok"
                                 otherButtonTitles:nil];
    else
        alert = [[UIAlertView alloc] initWithTitle:@"Success"
                                           message:@"Image saved to Photo Album."
                                          delegate:self cancelButtonTitle:@"Ok"
                                 otherButtonTitles:nil];
    [alert show];
    // [alert release];
}