How to save composite or modified image for iOS Development?

I added an overlay to my image (selected from photo album) and I can't save the composite, the following code only saves the original image. Any one out have a suggestion to modify the image object to have the added image?

    #pragma mark -
- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info 
{   
    imageView.image = [info objectForKey:@"UIImagePickerControllerOriginalImage"];
    OverlayView *overlay = [[OverlayView alloc] initWithFrame:CGRectMake(0, 0, SCREEN_WIDTH, SCREEN_HEIGTH)];
    overlay.alpha = 0.6;  // Customize the opacity of the top image.
    [imageView addSubview:overlay];
    CGContextRef context = U开发者_如何学PythonIGraphicsGetCurrentContext();
    //UIImage *imageCopy = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
        // Save image
    UIImageWriteToSavedPhotosAlbum(imageView.image, self,                                    @selector(image:didFinishSavingWithError:contextInfo:), context);
    [picker dismissModalViewControllerAnimated:YES];
}

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UIImageWriteToSavedPhotosAlbum(imageView.image.layer, self)

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Thank you @Rahul Vyas. I didn't try your suggestion, but I still appreciate your input. Ended up getting this issue resolved from help from the Apple Dev forums.

The answer to this problem is, as it worked for me:

CGRect screenRect = [[UIScreen mainScreen] bounds];    
UIGraphicsBeginImageContext(screenRect.size);
CGContextRef context = UIGraphicsGetCurrentContext(); 
[[UIColor blackColor] set]; 
CGContextFillRect(context, screenRect);
[imageView.layer renderInContext:context];
UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Save image
UIImageWriteToSavedPhotosAlbum(newImage, self, @selector(image:didFinishSavingWithError:contextInfo:), context);
[picker dismissModalViewControllerAnimated:YES];